Forecasting and the importance of being uncertain
Forecasting and the
importance of being
uncertain
Rob J Hyndman
1
Forecasting and the importance of being uncertain
Speaker introduction
Rob J Hyndman
Professor of Statistics, Monash University
2
Forecasting and the importance of being uncertain
Speaker introduction
Rob J Hyndman
Professor of Statistics, Monash University
Director, Business & Economic Forecasting
Unit, Monash University
2
Forecasting and the importance of being uncertain
Speaker introduction
Rob J Hyndman
Professor of Statistics, Monash University
Director, Business & Economic Forecasting
Unit, Monash University
Editor-in-Chief,
International Journal of Forecasting
2
Forecasting and the importance of being uncertain
Speaker introduction
Rob J Hyndman
Professor of Statistics, Monash University
Director, Business & Economic Forecasting
Unit, Monash University
Editor-in-Chief,
International Journal of Forecasting
Director, International Institute of
Forecasters
2
Forecasting and the importance of being uncertain
Speaker introduction
Rob J Hyndman
Professor of Statistics, Monash University
Director, Business & Economic Forecasting
Unit, Monash University
Editor-in-Chief,
International Journal of Forecasting
Director, International Institute of
Forecasters
Co-author of textbook,
Forecasting: methods and applications.
2
Forecasting and the importance of being uncertain
Forecasters are to blame!
News report on 16 August 2006
A Russian woman is suing weather forecasters
for wrecking her holiday. A court in Uljanovsk
heard that Alyona Gabitova had been promised
28 degrees and sunshine when she planned a
camping trip to a local nature reserve,
newspaper Nowyje Iswestija said.
But it did nothing but pour with rain the whole
time, leaving her with a cold. Gabitova has
asked the court to order the weather service to
pay the cost of her travel.
3
Forecasting and the importance of being uncertain
A brief history of forecasting
Outline
1
A brief history of forecasting
2
Forecasting the PBS
3
Forecasting CO2 emissions
4
Forecasting Australia’s population
5
Forecasting peak electricity demand
6
Forecast evaluation
7
Conclusions
4
Forecasting and the importance of being uncertain
What is it?
A brief history of forecasting
5
Forecasting and the importance of being uncertain
What is it?
Clay model of
sheep’s liver
Used by
Babylonian
forecasters
approximately
600 B.C.
Now in British Museum.
A brief history of forecasting
5
Forecasting and the importance of being uncertain
Delphic oracle
A brief history of forecasting
6
Forecasting and the importance of being uncertain
Delphic oracle
A brief history of forecasting
6
Forecasting and the importance of being uncertain
Delphic oracle
A brief history of forecasting
6
Forecasting and the importance of being uncertain
Temple of Apollo
A brief history of forecasting
7
Forecasting and the importance of being uncertain
Temple of Apollo
A brief history of forecasting
7
Forecasting and the importance of being uncertain
Temple of Apollo
A brief history of forecasting
7
Forecasting and the importance of being uncertain
A brief history of forecasting
Vagrant forecasters
The British Vagrancy Act (1736)
made it an offence to defraud by
charging money
for predictions.
8
Forecasting and the importance of being uncertain
A brief history of forecasting
Vagrant forecasters
The British Vagrancy Act (1736)
made it an offence to defraud by
charging money
for predictions.
Punishment: a
fine or three
months’
imprisonment
with hard labour.
8
Forecasting and the importance of being uncertain
A brief history of forecasting
Reputations can be made and lost
“Tell us what the future holds, so we may know that
you are gods.”
(Isaiah 41:23, 700 B.C.)
9
Forecasting and the importance of being uncertain
A brief history of forecasting
Reputations can be made and lost
“Tell us what the future holds, so we may know that
you are gods.”
(Isaiah 41:23, 700 B.C.)
“I think there is a world market for maybe five
computers.”
(Chairman of IBM, 1943)
9
Forecasting and the importance of being uncertain
A brief history of forecasting
Reputations can be made and lost
“Tell us what the future holds, so we may know that
you are gods.”
(Isaiah 41:23, 700 B.C.)
“I think there is a world market for maybe five
computers.”
(Chairman of IBM, 1943)
“Computers in the future may weigh no more than
1.5 tons.”
(Popular Mechanics, 1949)
9
Forecasting and the importance of being uncertain
A brief history of forecasting
Reputations can be made and lost
“Tell us what the future holds, so we may know that
you are gods.”
(Isaiah 41:23, 700 B.C.)
“I think there is a world market for maybe five
computers.”
(Chairman of IBM, 1943)
“Computers in the future may weigh no more than
1.5 tons.”
(Popular Mechanics, 1949)
“There is no reason anyone would want a computer
in their home.”
(President, DEC, 1977)
9
Forecasting and the importance of being uncertain
A brief history of forecasting
Reputations can be made and lost
“Tell us what the future holds, so we may know that
you are gods.”
(Isaiah 41:23, 700 B.C.)
“I think there is a world market for maybe five
computers.”
(Chairman of IBM, 1943)
“Computers in the future may weigh no more than
1.5 tons.”
(Popular Mechanics, 1949)
“There is no reason anyone would want a computer
in their home.”
(President, DEC, 1977)
“There are four ways economists can lose their
reputation. Gambling is the quickest, sex is the most
pleasurable and drink the slowest. But forecasting is
the surest.”
(Max Walsh, The Age, 1993)
9
Forecasting and the importance of being uncertain
A brief history of forecasting
Those “unforeseen events”
Precautions should be taken
against running into unforeseen
occurrences or
events.
(Horoscope, New York Times)
10
Forecasting and the importance of being uncertain
A brief history of forecasting
Those “unforeseen events”
Precautions should be taken
against running into unforeseen
occurrences or
events.
(Horoscope, New York Times)
We are ready for any
unforeseen event which may or
may not occur.
(Dan Quayle)
10
Forecasting
the by
importance
of being
businessand
plan
importing
youruncertain
balances.
A brief
history of forecasting
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Forecasting and the importance of being uncertain
A brief history of forecasting
Standard business practice today
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Forecasting and the importance of being uncertain
A brief history of forecasting
Standard business practice today
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11
Forecasting and the importance of being uncertain
A brief history of forecasting
Standard business practice today
“What-if scenarios” based on assumed and
fixed future conditions.
12
Forecasting and the importance of being uncertain
A brief history of forecasting
Standard business practice today
“What-if scenarios” based on assumed and
fixed future conditions.
Highly subjective.
12
Forecasting and the importance of being uncertain
A brief history of forecasting
Standard business practice today
“What-if scenarios” based on assumed and
fixed future conditions.
Highly subjective.
Not replicable or testable.
12
Forecasting and the importance of being uncertain
A brief history of forecasting
Standard business practice today
“What-if scenarios” based on assumed and
fixed future conditions.
Highly subjective.
Not replicable or testable.
No possible way of quantifying
probabilistic uncertainty.
12
Forecasting and the importance of being uncertain
A brief history of forecasting
Standard business practice today
“What-if scenarios” based on assumed and
fixed future conditions.
Highly subjective.
Not replicable or testable.
No possible way of quantifying
probabilistic uncertainty.
Lack of uncertainty statements leads to
false sense of accuracy.
12
Forecasting and the importance of being uncertain
A brief history of forecasting
Standard business practice today
“What-if scenarios” based on assumed and
fixed future conditions.
Highly subjective.
Not replicable or testable.
No possible way of quantifying
probabilistic uncertainty.
Lack of uncertainty statements leads to
false sense of accuracy.
Largely guesswork.
12
Forecasting and the importance of being uncertain
A brief history of forecasting
Standard business practice today
“What-if scenarios” based on assumed and
fixed future conditions.
Highly subjective.
Not replicable or testable.
No possible way of quantifying
probabilistic uncertainty.
Lack of uncertainty statements leads to
false sense of accuracy.
Largely guesswork.
12
Forecasting and the importance of being uncertain
A brief history of forecasting
Standard business practice today
“What-if scenarios” based on assumed and
fixed future conditions.
Highly subjective.
Not replicable or testable.
No possible way of quantifying
probabilistic uncertainty.
Lack of uncertainty statements leads to
false sense of accuracy.
Largely guesswork.
Is this any better than a sheep’s liver or
hallucinogens?
12
Forecasting and the importance of being uncertain
A brief history of forecasting
13
The rise of stochastic models
1959 exponential smoothing (Brown)
1970 ARIMA models (Box, Jenkins)
1980 VAR models (Sims, Granger)
1980 non-linear models (Granger, Tong, Hamilton,
Teräsvirta, . . . )
1982 ARCH/GARCH (Engle, Bollerslev)
1986 neural networks (Rumelhart)
1989 state space models (Harvey, West, Harrison)
1994 nonparametric forecasting (Tjøstheim, Härdle,
Tsay,. . . )
Forecasting and the importance of being uncertain
A brief history of forecasting
Advantages of stochastic models
Based on empirical data
14
Forecasting and the importance of being uncertain
A brief history of forecasting
Advantages of stochastic models
Based on empirical data
Computable
14
Forecasting and the importance of being uncertain
A brief history of forecasting
Advantages of stochastic models
Based on empirical data
Computable
Replicable
14
Forecasting and the importance of being uncertain
A brief history of forecasting
Advantages of stochastic models
Based on empirical data
Computable
Replicable
Testable
14
Forecasting and the importance of being uncertain
A brief history of forecasting
Advantages of stochastic models
Based on empirical data
Computable
Replicable
Testable
Objective measure of uncertainty
14
Forecasting and the importance of being uncertain
A brief history of forecasting
Advantages of stochastic models
Based on empirical data
Computable
Replicable
Testable
Objective measure of uncertainty
Able to compute prediction intervals
14
Forecasting and the importance of being uncertain
Forecasting the PBS
Outline
1
A brief history of forecasting
2
Forecasting the PBS
3
Forecasting CO2 emissions
4
Forecasting Australia’s population
5
Forecasting peak electricity demand
6
Forecast evaluation
7
Conclusions
15
Forecasting and the importance of being uncertain
Forecasting the PBS
Forecasting the PBS
16
Forecasting and the importance of being uncertain
Forecasting the PBS
Forecasting the PBS
Estimation of forward estimates for the
Pharmaceutical Benefit Scheme
Department of Health and Aging
$5 billion budget. Underforecasted by
$500–$800 million in 2000 and 2001.
17
Forecasting and the importance of being uncertain
Forecasting the PBS
Forecasting the PBS
Estimation of forward estimates for the
Pharmaceutical Benefit Scheme
Department of Health and Aging
$5 billion budget. Underforecasted by
$500–$800 million in 2000 and 2001.
Thousands of products. Seasonal demand.
17
Forecasting and the importance of being uncertain
Forecasting the PBS
Forecasting the PBS
Estimation of forward estimates for the
Pharmaceutical Benefit Scheme
Department of Health and Aging
$5 billion budget. Underforecasted by
$500–$800 million in 2000 and 2001.
Thousands of products. Seasonal demand.
Subject to covert marketing, volatile
products, uncontrollable expenditure.
17
Forecasting and the importance of being uncertain
Forecasting the PBS
Forecasting the PBS
Estimation of forward estimates for the
Pharmaceutical Benefit Scheme
Department of Health and Aging
$5 billion budget. Underforecasted by
$500–$800 million in 2000 and 2001.
Thousands of products. Seasonal demand.
Subject to covert marketing, volatile
products, uncontrollable expenditure.
All forecasts being done with the FORECAST
function in MS-Excel applied to 10 year old
data!
17
Forecasting and the importance of being uncertain
Forecasting the PBS
Forecasting the PBS
Estimation of forward estimates for the
Pharmaceutical Benefit Scheme
Department of Health and Aging
We used time series models —
automated exponential smoothing state
space modelling applied to about 100
product groups.
18
Forecasting and the importance of being uncertain
Forecasting the PBS
Forecasting the PBS
Estimation of forward estimates for the
Pharmaceutical Benefit Scheme
Department of Health and Aging
We used time series models —
automated exponential smoothing state
space modelling applied to about 100
product groups.
Methodological tools developed in 2002
and published in the International Journal
of Forecasting
18
Forecasting and the importance of being uncertain
Forecasting the PBS
Forecasting the PBS
Estimation of forward estimates for the
Pharmaceutical Benefit Scheme
Department of Health and Aging
We used time series models —
automated exponential smoothing state
space modelling applied to about 100
product groups.
Methodological tools developed in 2002
and published in the International Journal
of Forecasting
Forecast error now a few $million per year.
18
Forecasting and the importance of being uncertain
Forecasting the PBS
Total monthly scripts: concession copayments
Cardiovascular system drugs
80
60
40
80% prediction intervals
20
x 1000
100
120
140
Forecasting the PBS
1995
2000
Year
2005
19
Forecasting and the importance of being uncertain
Forecasting the PBS
Used stochastic models to describe
evolution of sales over time.
Forecasting the PBS
20
Forecasting and the importance of being uncertain
Forecasting the PBS
Forecasting the PBS
Used stochastic models to describe
evolution of sales over time.
Models allowed for time-changing trend
and seasonal patterns.
20
Forecasting and the importance of being uncertain
Forecasting the PBS
Forecasting the PBS
Used stochastic models to describe
evolution of sales over time.
Models allowed for time-changing trend
and seasonal patterns.
Stochastic models provide prediction
intervals which give a sense of uncertainty.
20
Forecasting and the importance of being uncertain
Forecasting the PBS
Forecasting the PBS
Used stochastic models to describe
evolution of sales over time.
Models allowed for time-changing trend
and seasonal patterns.
Stochastic models provide prediction
intervals which give a sense of uncertainty.
Class of models was based on exponential
smoothing.
20
Forecasting and the importance of being uncertain
Forecasting the PBS
Forecasting the PBS
Used stochastic models to describe
evolution of sales over time.
Models allowed for time-changing trend
and seasonal patterns.
Stochastic models provide prediction
intervals which give a sense of uncertainty.
Class of models was based on exponential
smoothing.
At the time, exponential smoothing
methods were not thought to be based on
stochastic models.
20
Forecasting and the importance of being uncertain
Forecasting the PBS
Exponential smoothing
Exponential smoothing is extremely
popular, simple to implement, and
performs well in forecasting competitions.
21
Forecasting and the importance of being uncertain
Forecasting the PBS
Exponential smoothing
Exponential smoothing is extremely
popular, simple to implement, and
performs well in forecasting competitions.
“Unfortunately, exponential
smoothing methods do not
allow easy calculation of prediction intervals.”
Makridakis, Wheelwright
and Hyndman, p.177.
(Wiley, 3rd ed., 1998)
21
Forecasting and the importance of being uncertain
Forecasting the PBS
Exponential smoothing
Since 2002. . .
a general class of state space models
proposed underlying all the common
exponential smoothing methods.
22
Forecasting and the importance of being uncertain
Forecasting the PBS
Exponential smoothing
Since 2002. . .
a general class of state space models
proposed underlying all the common
exponential smoothing methods.
analytical results for prediction intervals.
22
Forecasting and the importance of being uncertain
Forecasting the PBS
Exponential smoothing
Since 2002. . .
a general class of state space models
proposed underlying all the common
exponential smoothing methods.
analytical results for prediction intervals.
efficient parameter estimation.
22
Forecasting and the importance of being uncertain
Forecasting the PBS
Exponential smoothing
Since 2002. . .
a general class of state space models
proposed underlying all the common
exponential smoothing methods.
analytical results for prediction intervals.
efficient parameter estimation.
objective model selection.
22
Forecasting and the importance of being uncertain
Forecasting the PBS
Exponential smoothing
Since 2002. . .
a general class of state space models
proposed underlying all the common
exponential smoothing methods.
analytical results for prediction intervals.
efficient parameter estimation.
objective model selection.
an algorithm for automatic forecasting
using the new class of models.
22
Forecasting and the importance of being uncertain
Forecasting the PBS
Exponential smoothing
Since 2002. . .
a general class of state space models
proposed underlying all the common
exponential smoothing methods.
analytical results for prediction intervals.
efficient parameter estimation.
objective model selection.
an algorithm for automatic forecasting
using the new class of models.
new results on the admissible parameter
space.
22
Forecasting and the importance of being uncertain
Forecasting the PBS
Taxonomy of models
Trend
Component
Seasonal Component
N
A
M
(None) (Additive) (Multiplicative)
N
(None)
N,N
N,A
N,M
A
(Additive)
A,N
A,A
A,M
Ad
(Additive damped)
Ad ,N
M
(Multiplicative)
M,N
Ad ,A
M,A
Ad ,M
M,M
Md
(Multiplicative damped)
Md ,N
Md ,A
Md ,M
23
Forecasting and the importance of being uncertain
Forecasting the PBS
Taxonomy of models
Trend
Component
Seasonal Component
N
A
M
(None) (Additive) (Multiplicative)
N
(None)
N,N
N,A
N,M
A
(Additive)
A,N
A,A
A,M
Ad
(Additive damped)
Ad ,N
M
(Multiplicative)
M,N
Ad ,A
M,A
Ad ,M
M,M
Md
(Multiplicative damped)
Md ,N
Md ,A
Md ,M
General notation ETS(Error,Trend,Seasonal)
23
Forecasting and the importance of being uncertain
Forecasting the PBS
Taxonomy of models
Trend
Component
Seasonal Component
N
A
M
(None) (Additive) (Multiplicative)
N
(None)
N,N
N,A
N,M
A
(Additive)
A,N
A,A
A,M
Ad
(Additive damped)
Ad ,N
M
(Multiplicative)
M,N
Ad ,A
M,A
Ad ,M
M,M
Md
(Multiplicative damped)
Md ,N
Md ,A
Md ,M
General notation ETS(Error,Trend,Seasonal)
ExponenTial Smoothing
23
Forecasting and the importance of being uncertain
Forecasting the PBS
Taxonomy of models
Trend
Component
Seasonal Component
N
A
M
(None) (Additive) (Multiplicative)
N
(None)
N,N
N,A
N,M
A
(Additive)
A,N
A,A
A,M
Ad
(Additive damped)
Ad ,N
M
(Multiplicative)
M,N
Ad ,A
M,A
Ad ,M
M,M
Md
(Multiplicative damped)
Md ,N
Md ,A
Md ,M
General notation ETS(Error,Trend,Seasonal)
ExponenTial Smoothing
ETS(A,N,N): Simple exponential smoothing with
additive errors
23
Forecasting and the importance of being uncertain
Forecasting the PBS
Taxonomy of models
Trend
Component
Seasonal Component
N
A
M
(None) (Additive) (Multiplicative)
N
(None)
N,N
N,A
N,M
A
(Additive)
A,N
A,A
A,M
Ad
(Additive damped)
Ad ,N
M
(Multiplicative)
M,N
Ad ,A
M,A
Ad ,M
M,M
Md
(Multiplicative damped)
Md ,N
Md ,A
Md ,M
General notation ETS(Error,Trend,Seasonal)
ExponenTial Smoothing
ETS(A,A,N): Holt’s linear method with additive
errors
23
Forecasting and the importance of being uncertain
Forecasting the PBS
Taxonomy of models
Trend
Component
Seasonal Component
N
A
M
(None) (Additive) (Multiplicative)
N
(None)
N,N
N,A
N,M
A
(Additive)
A,N
A,A
A,M
Ad
(Additive damped)
Ad ,N
M
(Multiplicative)
M,N
Ad ,A
M,A
Ad ,M
M,M
Md
(Multiplicative damped)
Md ,N
Md ,A
Md ,M
General notation ETS(Error,Trend,Seasonal)
ExponenTial Smoothing
ETS(A,A,A): Additive Holt-Winters’ method with
additive errors
23
Forecasting and the importance of being uncertain
Forecasting the PBS
Taxonomy of models
Trend
Component
Seasonal Component
N
A
M
(None) (Additive) (Multiplicative)
N
(None)
N,N
N,A
N,M
A
(Additive)
A,N
A,A
A,M
Ad
(Additive damped)
Ad ,N
M
(Multiplicative)
M,N
Ad ,A
M,A
Ad ,M
M,M
Md
(Multiplicative damped)
Md ,N
Md ,A
Md ,M
General notation ETS(Error,Trend,Seasonal)
ExponenTial Smoothing
ETS(M,A,M): Multiplicative Holt-Winters’ method
with multiplicative errors
23
Forecasting and the importance of being uncertain
Forecasting the PBS
Taxonomy of models
Trend
Component
Seasonal Component
N
A
M
(None) (Additive) (Multiplicative)
N
(None)
N,N
N,A
N,M
A
(Additive)
A,N
A,A
A,M
Ad
(Additive damped)
Ad ,N
Ad ,A
M
(Multiplicative)
M,N
M,A
Ad ,M
M,M
Md
(Multiplicative damped)
Md ,N
Md ,A
Md ,M
General notation ETS(Error,Trend,Seasonal)
ExponenTial Smoothing
ETS(A,Ad ,N): Damped trend method with additive errors
23
Forecasting and the importance of being uncertain
Forecasting the PBS
Taxonomy of models
Trend
Component
Seasonal Component
N
A
M
(None) (Additive) (Multiplicative)
N
(None)
N,N
N,A
N,M
A
(Additive)
A,N
A,A
A,M
Ad
(Additive damped)
Ad ,N
M
(Multiplicative)
M,N
Ad ,A
M,A
Ad ,M
M,M
Md
(Multiplicative damped)
Md ,N
Md ,A
Md ,M
General notation ETS(Error,Trend,Seasonal)
ExponenTial Smoothing
There are 30 separate models in the ETS
framework
23
Forecasting and the importance of being uncertain
Forecasting the PBS
24
New book!
Springer Series in Statistics
Rob J. Hyndman · Anne B. Koehler
J. Keith Ord · Ralph D. Snyder
Forecasting
with Exponential
Smoothing
The State Space Approach
13
State space modeling
framework
Prediction intervals
Model selection
Maximum likelihood
estimation
All the important research
results in one place with
consistent notation
Many new results
375 pages but only
US$54.95 / £28.50 / e36.95
Forecasting and the importance of being uncertain
Forecasting the PBS
24
New book!
State space modeling
framework
Prediction intervals
Rob J. Hyndman · Anne B. Koehler
Model selection
J. Keith Ord · Ralph D. Snyder
Maximum likelihood
Forecasting
estimation
with Exponential
All the important research
Smoothing
results in one place with
consistent notation
The State Space Approach
Many new results
375 pages but only
13
US$54.95 / £28.50 / e36.95
www.exponentialsmoothing.net
Springer Series in Statistics
Forecasting and the importance of being uncertain
Forecasting CO2 emissions
Outline
1
A brief history of forecasting
2
Forecasting the PBS
3
Forecasting CO2 emissions
4
Forecasting Australia’s population
5
Forecasting peak electricity demand
6
Forecast evaluation
7
Conclusions
25
Forecasting and the importance of being uncertain
Forecasting CO2 emissions
Forecasting CO2 emissions
Australian Greenhouse Office
Task: produce multi-year forecasts of
Australia’s CO2 emissions with uncertainty
limits.
26
Forecasting and the importance of being uncertain
Forecasting CO2 emissions
Forecasting CO2 emissions
Australian Greenhouse Office
Task: produce multi-year forecasts of
Australia’s CO2 emissions with uncertainty
limits.
Problems: very little reliable data. Likely
major changes in technology making
historical data of little value.
26
Forecasting and the importance of being uncertain
Forecasting CO2 emissions
Forecasting CO2 emissions
Australian Greenhouse Office
Task: produce multi-year forecasts of
Australia’s CO2 emissions with uncertainty
limits.
Problems: very little reliable data. Likely
major changes in technology making
historical data of little value.
Solution: Use judgmental methods
26
Forecasting and the importance of being uncertain
Forecasting CO2 emissions
Forecasting CO2 emissions
: Expert Review of Emissions Projections Methodology
Australian Greenhouse Office
Key drivers ‘high’ and
‘low’ scenarios for sector
Expert
A
Expert
B
Expert A’s best
estimate & 95%
confidence
interval
Expert B’s best
estimate & 95%
confidence
interval
Expert C’s best
estimate & 95%
confidence
interval
emissions
Expert E’s best
estimate & 95%
confidence
interval
best
low
best
high
emissions
low
high
probability
high
probability
probability
emissions
low
high
probability
low
Expert
E
Expert D’s best
estimate & 95%
confidence
interval
best
best
high
Expert
D
probability
best
low
Expert
C
emissions
emissions
27
Forecasting and the importance of being uncertain
Expert A’s best
estimate & 95%
confidence
interval
Expert B’s best
estimate & 95%
confidence
interval
CO
Expert Forecasting
C’s best Expert D’s
best2
estimate & 95% estimate & 95%
confidence
confidence
interval
interval
Forecasting CO2 emissions
best
low
best
best
high
low
low
high
high
emissions
Expert E’s best
best
low
27
estimate & 95%
confidence
interval
best
high
low
high
: Expert Review of Emissions Projections Methodology
emissions
Expert
A
Expert
B
Expert
C
Expert
D
emissions
probability
probability
probability
probability
Key drivers ‘high’ and
‘low’ scenarios for sector
probability
Australian Greenhouse Office
emissions
emissions
emissions
Expert
E
R3 Correlations module
Expert B’s best
estimate & 95%
confidence
interval
best
low
Expert C’s best
estimate & 95%
confidence
interval
low
low
high
Expert E’s best
estimate & 95%
confidence
interval
best
best
best
high
Expert D’s best
estimate & 95%
confidence
interval
high
low
best
high
low
high
probability
Expert A’s best
estimate & 95%
confidence
interval
Combined sectoral
projection
low
high
emissions
emissions
probability
Figure 2: Effect of triangular distributions on combined sectoral projection distribution
probability
probability
probability
probability
best
Actual emissions distribution
emissions
emissions
emissions
Monash University Department of Econometrics and Business Statistics
Forecasting and the importance of being uncertain
Forecasting Australia’s population
Outline
1
A brief history of forecasting
2
Forecasting the PBS
3
Forecasting CO2 emissions
4
Forecasting Australia’s population
5
Forecasting peak electricity demand
6
Forecast evaluation
7
Conclusions
28
Forecasting and the importance of being uncertain
Forecasting Australia’s population
ABS population projections
The Australian Bureau of Statistics provide
population “projections”.
“The projections are not intended as predictions or
forecasts, but are illustrations of growth and change in
the population that would occur if assumptions made
about future demographic trends were to prevail over
the projection period.
While the assumptions are formulated on the basis of an
assessment of past demographic trends, both in
Australia and overseas, there is no certainty that any of
the assumptions will be realised. In addition, no
assessment has been made of changes in
non-demographic conditions.”
ABS 3222.0 - Population Projections, Australia, 2004 to 2101
29
Forecasting and the importance of being uncertain
Forecasting Australia’s population
ABS population projections
The ABS provides three projection scenarios
labelled “High”, “Medium” and “Low”.
Based on assumed mortality, fertility and
migration rates
30
Forecasting and the importance of being uncertain
Forecasting Australia’s population
ABS population projections
The ABS provides three projection scenarios
labelled “High”, “Medium” and “Low”.
Based on assumed mortality, fertility and
migration rates
No objectivity.
30
Forecasting and the importance of being uncertain
Forecasting Australia’s population
ABS population projections
The ABS provides three projection scenarios
labelled “High”, “Medium” and “Low”.
Based on assumed mortality, fertility and
migration rates
No objectivity.
No dynamic changes in rates allowed
30
Forecasting and the importance of being uncertain
Forecasting Australia’s population
ABS population projections
The ABS provides three projection scenarios
labelled “High”, “Medium” and “Low”.
Based on assumed mortality, fertility and
migration rates
No objectivity.
No dynamic changes in rates allowed
No variation allowed across ages.
30
Forecasting and the importance of being uncertain
Forecasting Australia’s population
ABS population projections
The ABS provides three projection scenarios
labelled “High”, “Medium” and “Low”.
Based on assumed mortality, fertility and
migration rates
No objectivity.
No dynamic changes in rates allowed
No variation allowed across ages.
No probabilistic basis.
30
Forecasting and the importance of being uncertain
Forecasting Australia’s population
ABS population projections
The ABS provides three projection scenarios
labelled “High”, “Medium” and “Low”.
Based on assumed mortality, fertility and
migration rates
No objectivity.
No dynamic changes in rates allowed
No variation allowed across ages.
No probabilistic basis.
Not prediction intervals.
30
Forecasting and the importance of being uncertain
Forecasting Australia’s population
ABS population projections
The ABS provides three projection scenarios
labelled “High”, “Medium” and “Low”.
Based on assumed mortality, fertility and
migration rates
No objectivity.
No dynamic changes in rates allowed
No variation allowed across ages.
No probabilistic basis.
Not prediction intervals.
Most users use the “Medium” projection,
but it is unrelated to the mean, median or
mode of the future distribution.
30
Forecasting and the importance of being uncertain
Forecasting Australia’s population
ABS population projections
Australian total population
30
A
25
B
20
15
10
5
Millions
C
1920
1940
1960
1980
Year
2000
2020
2040
31
Forecasting and the importance of being uncertain
Forecasting Australia’s population
ABS population projections
Australian total population
30
A
25
B
20
15
10
5
Millions
C
1920
1940
1960
1980
2000
2020
2040
Year
What do these projections mean?
31
Forecasting and the importance of being uncertain
Forecasting Australia’s population
Annual age-specific population
100000
50000
0
Population
150000
Australia: male population (1921)
0
20
40
60
Age
80
100
32
Forecasting and the importance of being uncertain
Forecasting Australia’s population
Annual age-specific population
100000
50000
0
Population
150000
Australia: male population (1921−2004)
0
20
40
60
Age
80
100
33
Forecasting and the importance of being uncertain
Forecasting Australia’s population
Annual age-specific population
100000
50000
0
Population
150000
Australia: female population (1921−2004)
0
20
40
60
Age
80
100
33
Forecasting and the importance of being uncertain
Forecasting Australia’s population
34
Stochastic population forecasts
Key ideas
Population is a function of mortality,
fertility and net migration.
Forecasting and the importance of being uncertain
Forecasting Australia’s population
34
Stochastic population forecasts
Key ideas
Population is a function of mortality,
fertility and net migration.
Build an age-sex-specific stochastic model
for each of mortality, fertility & net migration.
Forecasting and the importance of being uncertain
Forecasting Australia’s population
34
Stochastic population forecasts
Key ideas
Population is a function of mortality,
fertility and net migration.
Build an age-sex-specific stochastic model
for each of mortality, fertility & net migration.
Use the models to simulate future
sample paths of all components.
Forecasting and the importance of being uncertain
Forecasting Australia’s population
34
Stochastic population forecasts
Key ideas
Population is a function of mortality,
fertility and net migration.
Build an age-sex-specific stochastic model
for each of mortality, fertility & net migration.
Use the models to simulate future
sample paths of all components.
Compute future births, deaths, net migrants
and populations from simulated rates.
Forecasting and the importance of being uncertain
Forecasting Australia’s population
34
Stochastic population forecasts
Key ideas
Population is a function of mortality,
fertility and net migration.
Build an age-sex-specific stochastic model
for each of mortality, fertility & net migration.
Use the models to simulate future
sample paths of all components.
Compute future births, deaths, net migrants
and populations from simulated rates.
Combine the results to get age-specific
stochastic population forecasts.
Forecasting and the importance of being uncertain
Forecasting Australia’s population
Mortality rates
−4
−6
−8
Log death rate
−2
0
Australia: male mortality (1921)
0
20
40
60
Age
80
100
35
Forecasting and the importance of being uncertain
Forecasting Australia’s population
Mortality rates
−4
−6
−8
Log death rate
−2
0
Australia: male death rates (1921−2003)
0
20
40
60
Age
80
100
36
Forecasting and the importance of being uncertain
Forecasting Australia’s population
Mortality rates
−4
−6
−8
−10
Log death rate
−2
0
Australia: male mortality (1921−2003)
0
20
40
60
Age
80
100
36
Forecasting and the importance of being uncertain
Forecasting Australia’s population
Mortality rates
−4
−6
−8
−10
Log death rate
−2
0
Australia: male mortality forecasts (2004−2023)
0
20
40
60
Age
80
100
36
Forecasting and the importance of being uncertain
Forecasting Australia’s population
Mortality rates
−4
−6
−8
−10
Log death rate
−2
0
Australia: male death rate forecasts (2004 and 2023)
80% prediction intervals
0
20
40
60
Age
80
100
36
Forecasting and the importance of being uncertain
Forecasting Australia’s population
Fertility rates
150
100
50
0
Fertility rate
200
250
Australia: fertility rates (1921)
15
20
25
30
35
Age
40
45
50
37
Forecasting and the importance of being uncertain
Forecasting Australia’s population
Fertility
150
100
50
0
Fertility rate
200
250
300
Australia: fertility rate forecasts (2004 and 2023)
15
20
25
30
35
Age
40
45
50
38
Forecasting and the importance of being uncertain
Forecasting Australia’s population
Fertility
150
100
50
0
Fertility rate
200
250
300
Australia: fertility rate forecasts (2004 and 2023)
15
20
25
30
35
Age
40
45
50
38
Forecasting and the importance of being uncertain
Forecasting Australia’s population
Fertility
150
100
50
0
Fertility rate
200
250
300
Australia: fertility rate forecasts (2004 and 2023)
15
20
25
30
35
Age
40
45
50
38
Forecasting and the importance of being uncertain
Forecasting Australia’s population
Fertility
300
Australia: fertility rate forecasts (2004 and 2023)
150
100
50
0
Fertility rate
200
250
80% prediction intervals
15
20
25
30
35
Age
40
45
50
38
Forecasting and the importance of being uncertain
Forecasting Australia’s population
Migration: male
1000
0
−1000
−2000
Net migration
2000
3000
Australia: male net migration (1973−2003)
0
20
40
60
Age
80
100
39
Forecasting and the importance of being uncertain
Forecasting Australia’s population
Migration: male
1000
0
−1000
−2000
Number people
2000
3000
Male net migration
0
20
40
60
Age
80
100
39
Forecasting and the importance of being uncertain
Forecasting Australia’s population
Forecasts of life expectancy at age 0
85
80
70
75
Age
70
75
Age
80
85
90
Forecast male life expectancy
90
Forecast female life expectancy
1960
1980
Year
2000
2020
1960
1980
Year
2000
2020
40
Forecasting and the importance of being uncertain
Forecasting Australia’s population
Forecasts of TFR
2500
2000
1500
TFR
3000
3500
Forecast Total Fertility Rate
1920
1940
1960
1980
Year
2000
2020
41
Forecasting and the importance of being uncertain
Forecasting Australia’s population
Population forecasts
Forecast population: 2024
70
150
100
50
0
50
100
150
Population ('000)
Forecast population pyramid for 2024, along with 80%
prediction intervals. Dashed: actual population pyramid
for 2004.
Age
50
0 10
30
50
30
0 10
Age
70
90
Female
90
Male
42
Forecasting and the importance of being uncertain
Forecasting Australia’s population
Population forecasts
11
10
9
7
8
Population (millions)
12
13
Total males
● ●
● ●
● ●
●
1980
●
●
●
●
●
●
●
●
●
●
1990
●
● ●
●
●
●
●
●
●
●
2000
●
● ●
2010
2020
Twenty-year forecasts of totalYear
population along with 80%
and 95% prediction intervals. Dashed: ABS (2006)
projections. Dotted: ABS (2003) projections.
43
Forecasting and the importance of being uncertain
Forecasting Australia’s population
Population forecasts
11
10
9
7
8
Population (millions)
12
13
Total females
●
● ●
● ●
●
●
1980
●
●
●
●
●
●
●
●
●
●
1990
●
●
●
●
●
●
●
●
●
●
2000
●
● ●
2010
2020
Twenty-year forecasts of totalYear
population along with 80%
and 95% prediction intervals. Dashed: ABS (2006)
projections. Dotted: ABS (2003) projections.
44
Forecasting and the importance of being uncertain
Forecasting Australia’s population
Old-age dependency ratio
0.20
0.15
0.10
ratio
0.25
0.30
0.35
Old−age dependency ratio forecasts
1920
1940
1960
1980
Year
2000
2020
45
Forecasting and the importance of being uncertain
Forecasting Australia’s population
46
Stochastic population forecasts
Forecasts represent the median of the future
distribution.
Forecasting and the importance of being uncertain
Forecasting Australia’s population
46
Stochastic population forecasts
Forecasts represent the median of the future
distribution.
Percentiles of distribution allow information about
uncertainty
Forecasting and the importance of being uncertain
Forecasting Australia’s population
46
Stochastic population forecasts
Forecasts represent the median of the future
distribution.
Percentiles of distribution allow information about
uncertainty
Prediction intervals with specified probability
coverage for population size and all derived
variables (total fertility rate, life expectancy,
old-age dependencies, etc.)
Forecasting and the importance of being uncertain
Forecasting Australia’s population
46
Stochastic population forecasts
Forecasts represent the median of the future
distribution.
Percentiles of distribution allow information about
uncertainty
Prediction intervals with specified probability
coverage for population size and all derived
variables (total fertility rate, life expectancy,
old-age dependencies, etc.)
The probability of future events can be estimated.
Forecasting and the importance of being uncertain
Forecasting Australia’s population
46
Stochastic population forecasts
Forecasts represent the median of the future
distribution.
Percentiles of distribution allow information about
uncertainty
Prediction intervals with specified probability
coverage for population size and all derived
variables (total fertility rate, life expectancy,
old-age dependencies, etc.)
The probability of future events can be estimated.
Economic planning is better based on prediction
intervals rather than mean or median forecasts.
Forecasting and the importance of being uncertain
Forecasting Australia’s population
46
Stochastic population forecasts
Forecasts represent the median of the future
distribution.
Percentiles of distribution allow information about
uncertainty
Prediction intervals with specified probability
coverage for population size and all derived
variables (total fertility rate, life expectancy,
old-age dependencies, etc.)
The probability of future events can be estimated.
Economic planning is better based on prediction
intervals rather than mean or median forecasts.
Stochastic models allow true policy analysis to be
carried out.
Forecasting and the importance of being uncertain
Forecasting peak electricity demand
Outline
1
A brief history of forecasting
2
Forecasting the PBS
3
Forecasting CO2 emissions
4
Forecasting Australia’s population
5
Forecasting peak electricity demand
6
Forecast evaluation
7
Conclusions
47
Forecasting and the importance of being uncertain
Forecasting peak electricity demand
The problem
We want to forecast the peak electricity
demand in a half-hour period in ten years
time.
48
Forecasting and the importance of being uncertain
Forecasting peak electricity demand
The problem
We want to forecast the peak electricity
demand in a half-hour period in ten years
time.
We have ten years of half-hourly electricity
data, temperature data and some
economic and demographic data.
48
Forecasting and the importance of being uncertain
Forecasting peak electricity demand
The problem
We want to forecast the peak electricity
demand in a half-hour period in ten years
time.
We have ten years of half-hourly electricity
data, temperature data and some
economic and demographic data.
The location is South Australia: home to
the most volatile electricity demand in the
world.
48
Forecasting and the importance of being uncertain
Forecasting peak electricity demand
The problem
We want to forecast the peak electricity
demand in a half-hour period in ten years
time.
We have ten years of half-hourly electricity
data, temperature data and some
economic and demographic data.
The location is South Australia: home to
the most volatile electricity demand in the
world.
48
Forecasting and the importance of being uncertain
Forecasting peak electricity demand
The problem
We want to forecast the peak electricity
demand in a half-hour period in ten years
time.
We have ten years of half-hourly electricity
data, temperature data and some
economic and demographic data.
The location is South Australia: home to
the most volatile electricity demand in the
world.
Sounds impossible?
48
Forecasting and the importance of being uncertain
Demand data
Forecasting peak electricity demand
49
Forecasting and the importance of being uncertain
Forecasting peak electricity demand
Demand data
2.0
1.5
1.0
SA demand (GW)
2.5
South Australian operational demand (summer 06/07)
Nov 06
Dec 06
Jan 07
Feb 07
Mar 07
50
Forecasting and the importance of being uncertain
Forecasting peak electricity demand
Demand data
2.0
1.5
SA demand (GW)
2.5
SA demand (first 3 weeks of January 2007)
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21
Date in January
51
Forecasting and the importance of being uncertain
Demand drivers
calendar effects
Forecasting peak electricity demand
52
Forecasting and the importance of being uncertain
Forecasting peak electricity demand
Demand drivers
calendar effects
prevailing weather conditions (and the
timing of those conditionals
52
Forecasting and the importance of being uncertain
Forecasting peak electricity demand
Demand drivers
calendar effects
prevailing weather conditions (and the
timing of those conditionals
climate changes
52
Forecasting and the importance of being uncertain
Forecasting peak electricity demand
Demand drivers
calendar effects
prevailing weather conditions (and the
timing of those conditionals
climate changes
economic and demographic changes
52
Forecasting and the importance of being uncertain
Forecasting peak electricity demand
Demand drivers
calendar effects
prevailing weather conditions (and the
timing of those conditionals
climate changes
economic and demographic changes
changing technology
52
Forecasting and the importance of being uncertain
Forecasting peak electricity demand
Demand drivers
calendar effects
prevailing weather conditions (and the
timing of those conditionals
climate changes
economic and demographic changes
changing technology
52
Forecasting and the importance of being uncertain
Forecasting peak electricity demand
Demand drivers
calendar effects
prevailing weather conditions (and the
timing of those conditionals
climate changes
economic and demographic changes
changing technology
Modelling framework
Semi-parametric additive models with
correlated errors.
52
Forecasting and the importance of being uncertain
Forecasting peak electricity demand
Demand drivers
calendar effects
prevailing weather conditions (and the
timing of those conditionals
climate changes
economic and demographic changes
changing technology
Modelling framework
Semi-parametric additive models with
correlated errors.
Each half-hour period modelled separately.
52
Forecasting and the importance of being uncertain
Forecasting peak electricity demand
52
Demand drivers
calendar effects
prevailing weather conditions (and the
timing of those conditionals
climate changes
economic and demographic changes
changing technology
Modelling framework
Semi-parametric additive models with
correlated errors.
Each half-hour period modelled separately.
Variables selected to provide best
out-of-sample predictions for 2005/06 summer.
Forecasting and the importance of being uncertain
Forecasting peak electricity demand
Actual
Fitted
1.45
1.40
1.35
1.30
1.25
Annual demand
1.50
1.55
Predictions
1998
2000
2002
Year
2004
2006
53
Forecasting and the importance of being uncertain
Forecasting peak electricity demand
53
Predictions
80
75
70
65
R−squared (%)
85
90
95
R−squared
12 midnight 3:00 am
6:00 am
9:00 am
12 noon
Time of day
3:00 pm
6:00 pm
9:00 pm 12 midnight
Forecasting and the importance of being uncertain
Forecasting peak electricity demand
Predictions
1.0
1.5
2.0
2.5
3.0
Actual demand
1998
2000
2002
2004
2006
Time
1.0
1.5
2.0
2.5
3.0
Predicted demand
1998
2000
2002
2004
2006
53
Forecasting and the importance of being uncertain
Forecasting peak electricity demand
2.0
1.5
1.0
Actual demand
2.5
3.0
Predictions
1.0
1.5
2.0
Predicted demand
2.5
3.0
53
Forecasting and the importance of being uncertain
Forecasting peak electricity demand
Peak demand distribution
Annual maximum
Base demand
1.0
0.5
Density
1.5
2007/2008
2008/2009
2009/2010
2010/2011
2011/2012
2012/2013
2013/2014
2014/2015
2015/2016
2016/2017
2017/2018
W)6
6
0.0
5
3
4
5
Demand (GW)
6
54
Forecasting and the importance of being uncertain
Forecasting peak electricity demand
3.0
3.5
4.0
90%
50%
10%
2%
●
●
●
●
●
●
●
2.5
Prob of exceedance in one year
Peak demand distribution
●
●
●
2000
2005
2010
Year
2015
54
Forecasting and the importance of being uncertain
Forecasting peak electricity demand
Forecasting peak electricity
demand
We have forecast the extreme upper tail in ten
years time using only ten years of data!
55
Forecasting and the importance of being uncertain
Forecasting peak electricity demand
Forecasting peak electricity
demand
We have forecast the extreme upper tail in ten
years time using only ten years of data!
This method has now been adopted for the official
South Australian, Victorian and Western Australian
peak electricity demand forecasts.
55
Forecasting and the importance of being uncertain
Forecasting peak electricity demand
Forecasting peak electricity
demand
We have forecast the extreme upper tail in ten
years time using only ten years of data!
This method has now been adopted for the official
South Australian, Victorian and Western Australian
peak electricity demand forecasts.
Method could also be used for short-term demand
forecasting, if we add a model for correlated
residuals.
55
Forecasting and the importance of being uncertain
Forecasting peak electricity demand
Forecasting peak electricity
demand
We have forecast the extreme upper tail in ten
years time using only ten years of data!
This method has now been adopted for the official
South Australian, Victorian and Western Australian
peak electricity demand forecasts.
Method could also be used for short-term demand
forecasting, if we add a model for correlated
residuals.
Provides way to analyse probability of coincident
peaks across different interconnected markets.
55
Forecasting and the importance of being uncertain
Forecasting peak electricity demand
Forecasting peak electricity
demand
We have forecast the extreme upper tail in ten
years time using only ten years of data!
This method has now been adopted for the official
South Australian, Victorian and Western Australian
peak electricity demand forecasts.
Method could also be used for short-term demand
forecasting, if we add a model for correlated
residuals.
Provides way to analyse probability of coincident
peaks across different interconnected markets.
Could be extended to whole year, providing
probabilistic forecasts of total energy requirements.
55
Forecasting and the importance of being uncertain
Forecast evaluation
Outline
1
A brief history of forecasting
2
Forecasting the PBS
3
Forecasting CO2 emissions
4
Forecasting Australia’s population
5
Forecasting peak electricity demand
6
Forecast evaluation
7
Conclusions
56
Forecasting and the importance of being uncertain
Forecast evaluation
Forecast evaluation
Ensure you have a systematic evaluation
process.
57
Forecasting and the importance of being uncertain
Forecast evaluation
Forecast evaluation
Ensure you have a systematic evaluation
process.
Check past forecasts against actuals.
57
Forecasting and the importance of being uncertain
Forecast evaluation
Forecast evaluation
Ensure you have a systematic evaluation
process.
Check past forecasts against actuals.
Check forecast driver variables against
actuals.
57
Forecasting and the importance of being uncertain
Forecast evaluation
Forecast evaluation
Ensure you have a systematic evaluation
process.
Check past forecasts against actuals.
Check forecast driver variables against
actuals.
Measure bias and variability.
57
Forecasting and the importance of being uncertain
Forecast evaluation
Forecast evaluation
Ensure you have a systematic evaluation
process.
Check past forecasts against actuals.
Check forecast driver variables against
actuals.
Measure bias and variability.
57
Forecasting and the importance of being uncertain
Forecast evaluation
Forecast evaluation
Ensure you have a systematic evaluation
process.
Check past forecasts against actuals.
Check forecast driver variables against
actuals.
Measure bias and variability.
Definitions
ã Bias: systematic under- or over-estimating
future value. Usually due to the method.
57
Forecasting and the importance of being uncertain
Forecast evaluation
Forecast evaluation
Ensure you have a systematic evaluation
process.
Check past forecasts against actuals.
Check forecast driver variables against
actuals.
Measure bias and variability.
Definitions
ã Bias: systematic under- or over-estimating
future value. Usually due to the method.
ã Variability: random (unpredictable)
errors. Usually due to the data.
57
Forecasting and the importance of being uncertain
Bias and variability
Forecast evaluation
58
Forecasting and the importance of being uncertain
Bias and variability
Forecast evaluation
59
Forecasting and the importance of being uncertain
Bias and variability
Forecast evaluation
60
Forecasting and the importance of being uncertain
Bias and variability
Forecast evaluation
61
Forecasting and the importance of being uncertain
Forecast evaluation
Bias and variability
Forecast bias is due to problems with the
forecasting method:
62
Forecasting and the importance of being uncertain
Forecast evaluation
Bias and variability
Forecast bias is due to problems with the
forecasting method:
Forecast method inappropriately chosen.
62
Forecasting and the importance of being uncertain
Forecast evaluation
Bias and variability
Forecast bias is due to problems with the
forecasting method:
Forecast method inappropriately chosen.
Data changes around time of forecast the
method does not allow for this change.
62
Forecasting and the importance of being uncertain
Forecast evaluation
Bias and variability
Forecast bias is due to problems with the
forecasting method:
Forecast method inappropriately chosen.
Data changes around time of forecast the
method does not allow for this change.
62
Forecasting and the importance of being uncertain
Forecast evaluation
Bias and variability
Forecast bias is due to problems with the
forecasting method:
Forecast method inappropriately chosen.
Data changes around time of forecast the
method does not allow for this change.
Forecast variability is due to unexplained
variation in the data:
62
Forecasting and the importance of being uncertain
Forecast evaluation
Bias and variability
Forecast bias is due to problems with the
forecasting method:
Forecast method inappropriately chosen.
Data changes around time of forecast the
method does not allow for this change.
Forecast variability is due to unexplained
variation in the data:
There are predictable sources of variation
in the data that have not been included in
the model.
62
Forecasting and the importance of being uncertain
Forecast evaluation
Bias and variability
Forecast bias is due to problems with the
forecasting method:
Forecast method inappropriately chosen.
Data changes around time of forecast the
method does not allow for this change.
Forecast variability is due to unexplained
variation in the data:
There are predictable sources of variation
in the data that have not been included in
the model.
There is unpredictable (random) variation
in the data.
62
Forecasting and the importance of being uncertain
Bias and variability
Measure of bias
Average of forecast errors.
Forecast evaluation
63
Forecasting and the importance of being uncertain
Forecast evaluation
Bias and variability
Measure of bias
Average of forecast errors.
Measure of variability
Average of absolute (or squared) forecast
errors.
63
Forecasting and the importance of being uncertain
Forecast evaluation
Bias and variability
Measure of bias
Average of forecast errors.
Measure of variability
Average of absolute (or squared) forecast
errors.
If you don’t use systematic forecast
evaluation, you will never learn from your
mistakes!
63
Forecasting and the importance of being uncertain
Conclusions
Outline
1
A brief history of forecasting
2
Forecasting the PBS
3
Forecasting CO2 emissions
4
Forecasting Australia’s population
5
Forecasting peak electricity demand
6
Forecast evaluation
7
Conclusions
64
Forecasting and the importance of being uncertain
Useful resources
Organization:
Conclusions
65
Forecasting and the importance of being uncertain
Useful resources
Organization:
ã International Institute of Forecasters.
Conclusions
65
Forecasting and the importance of being uncertain
Useful resources
Organization:
ã International Institute of Forecasters.
Websites:
Conclusions
65
Forecasting and the importance of being uncertain
Useful resources
Organization:
ã International Institute of Forecasters.
Websites:
ã www.forecasters.org
Conclusions
65
Forecasting and the importance of being uncertain
Useful resources
Organization:
ã International Institute of Forecasters.
Websites:
ã www.forecasters.org
ã www.forecastingprinciples.com
Conclusions
65
Forecasting and the importance of being uncertain
Useful resources
Organization:
ã International Institute of Forecasters.
Websites:
ã www.forecasters.org
ã www.forecastingprinciples.com
Conferences:
Conclusions
65
Forecasting and the importance of being uncertain
Useful resources
Organization:
ã International Institute of Forecasters.
Websites:
ã www.forecasters.org
ã www.forecastingprinciples.com
Conferences:
ã Forecasting Summit. September 2008, Boston.
Conclusions
65
Forecasting and the importance of being uncertain
Useful resources
Organization:
ã International Institute of Forecasters.
Websites:
ã www.forecasters.org
ã www.forecastingprinciples.com
Conferences:
ã Forecasting Summit. September 2008, Boston.
Journals:
Conclusions
65
Forecasting and the importance of being uncertain
Useful resources
Organization:
ã International Institute of Forecasters.
Websites:
ã www.forecasters.org
ã www.forecastingprinciples.com
Conferences:
ã Forecasting Summit. September 2008, Boston.
Journals:
ã International Journal of Forecasting
Conclusions
65
Forecasting and the importance of being uncertain
Useful resources
Organization:
ã International Institute of Forecasters.
Websites:
ã www.forecasters.org
ã www.forecastingprinciples.com
Conferences:
ã Forecasting Summit. September 2008, Boston.
Journals:
ã International Journal of Forecasting
ã Foresight
Conclusions
65
Forecasting and the importance of being uncertain
Useful resources
Organization:
ã International Institute of Forecasters.
Websites:
ã www.forecasters.org
ã www.forecastingprinciples.com
Conferences:
ã Forecasting Summit. September 2008, Boston.
Journals:
ã International Journal of Forecasting
ã Foresight
Conclusions
65
Forecasting and the importance of being uncertain
Conclusions
Useful resources
Organization:
ã International Institute of Forecasters.
Websites:
ã www.forecasters.org
ã www.forecastingprinciples.com
Conferences:
ã Forecasting Summit. September 2008, Boston.
Journals:
ã International Journal of Forecasting
ã Foresight
Links to all of the above at www.forecasters.org.
65
Forecasting and the importance of being uncertain
Conclusions
Applied Forecasting Journal
A PU BL I C AT I O N OF T HE INT ERNAT ION AL IN STI TU TE OF FOREC AST ERS
FORESIGHT
The International Journal of Applied Forecasting
T H E
E S S E N T I A L
R E A D
F O R
T H E
P R A C T I C I N G
Issue 9  Spring 2008
F O R E C A S T E R
Review of Competing on Analytics – The New Science of Winning
Hot New Research on Predicting the Demand for New Products
Sales Forecasting Innovations for Large-Scale Retailers
Prediction Markets for Pharmaceutical
Forecasting and Beyond
The Value of Information Sharing
in the Retail Supply Chain
Perils, Pitfalls, and Promises
of Long-Term Projections
Simulation/Risk Analysis: Review
of Three Software Packages
www.forecasters.org/foresight
The IIF, now in its 28th year, is the leading
non-profit clearinghouse of forecasting
theory, research and practice.
$40 per issue
66
Forecasting and the importance of being uncertain
Conclusions
Conclusions
Uncertainty statements are essential
when making predictions and should be
provided whether they are asked for or not.
67
Forecasting and the importance of being uncertain
Conclusions
Conclusions
Uncertainty statements are essential
when making predictions and should be
provided whether they are asked for or not.
Uncertainty statements can take the form
of prediction intervals or prediction densities.
67
Forecasting and the importance of being uncertain
Conclusions
Conclusions
Uncertainty statements are essential
when making predictions and should be
provided whether they are asked for or not.
Uncertainty statements can take the form
of prediction intervals or prediction densities.
A good forecaster is not smarter than everyone
else, he merely has his ignorance better
organised.
(Anonymous)
67
Forecasting and the importance of being uncertain
Conclusions
Conclusions
Uncertainty statements are essential
when making predictions and should be
provided whether they are asked for or not.
Uncertainty statements can take the form
of prediction intervals or prediction densities.
A good forecaster is not smarter than everyone
else, he merely has his ignorance better
organised.
(Anonymous)
Slides available from
www.robjhyndman.com
67