The numerical data that we will use in this course falls into
1 of 2 categories : discrete and continuous.
A type of data is discrete if there are only a finite number
of values possible or if there is a space on the number line between
each 2 possible values.
Ex. A 5 question quiz is given in a Math class. The number of
correct answers on a student's quiz is an example of discrete
data. The number of correct answers would have to be one of the
following : 0, 1, 2, 3, 4, or 5. There are not an infinite number
of values, therefore this data is discrete. Also, if we were to
draw a number line and place each possible value on it, we would
see a space between each pair of values.
Ex. In order to obtain a taxi license in Las Vegas, a person must
pass a written exam regarding different locations in the city.
How many times it would take a person to pass this test is also
an example of discrete data. A person could take it once, or twice,
or 3 times, or 4 times, or… . So, the possible values are
1, 2, 3, … . There are infinitely many possible values, but
if we were to put them on a number line, we would see a space
between each pair of values.
Discrete data usually occurs in a case where there are only a
certain number of values, or when we are counting something (using
whole numbers).
Continuous data makes up the rest of numerical data. This
is a type of data that is usually associated with some sort of
physical measurement.
Ex. The height of trees at a nursery is an example of continuous
data. Is it possible for a tree to be 76.2" tall? Sure. How
about 76.29"? Yes. How about 76.2914563782"? You betcha!
The possibilities depends upon the accuracy of our measuring device.
One general way to tell if data is continuous is to ask yourself
if it is possible for the data to take on values that are fractions
or decimals. If your answer is yes, this is usually continuous
data.
Ex. The length of time it takes for a light bulb to burn out is
an example of continuous data. Could it take 800 hours? How about
800.7? 800.7354? The answer to all 3 is yes.