
There are two types of measurement
 Quantitative measurements have a definite form
and are usually expressed as numbers with units.
▪ E.g. 3.05 grams, 12 liters, 4.5 grams/ml
 Qualitative measurements are descriptive and
have no numbers involved.
▪ E.g. It gave off a “reddish gas”, It had small bumps

Measurements can be either direct or
derived.
 Direct measurement can be taken straight from
an object.
▪ E.g. The length of an object in meters
 Derived measurements must have a
mathematical expression performed using several
direct measurements
▪ E.g. The volume of an object is length x width x height

Density is a very important derived
measurement.
 Density = Mass
Volume
Density is an example of an intensive property
because it does not depend on how much of the
object you have on hand.

How do you know if your measurement are
true or not?
 Accurate measurements are measurements that
are very close to the true value of a measurement.
 Precise measurements are measurements that
are consistent, but not necessarily close to the
true value.
 The goal is to have measurements that are both
accurate and precise.

Think of a dart board.
http://practicalanalyst.com/wp-content/uploads/2007/12/accuracy.jpg

The reliability of a measurement is expressed
by the number of significant figures that are
present.