MAT 133 Chapter 1 notes
The science of statistics teaches people how to gather, arrange, examine, and evaluate both
numerical and non-numerical data so they may make wise judgments. A trait that differs from
one person or item to another is called a variable. Variables under study may be either
numerically quantifiable or not (non numerical). An example of a numerical variable whose value
may be determined is height. Gender is a non-numerical variable, hence measuring it is
impossible. Gender cannot be measured. Both categorical nominal and categorical ordinal
categories can be applied to qualitative variables. Nominal categorical variables classify the
subject under study into groups or categories without regard to any inherent hierarchies. What,
for instance, is your preferred pizza topping—cheese, pepperoni, sausage, anchovies,
pineapple, etc.? A categorical ordinal variable classifies the subject under study into groups or
categories that each have a distinct inherent order. Which day of the week, such as Monday,
Tuesday, or Wednesday, would you prefer to have off? The next approaches for structuring your
findings can be used if your variables are categorical nominal or categorical ordinal:
Bar Diagrams (sometimes called Bar Charts)
Pie charts (sometimes called Circle Graphs)
