How do you compare apples and oranges?

• Are you as good a student of French as you are in Physics?
• How many people did better or worse than you on a test?
• Are you abnormal or deviant?
• Should you ask your professor to curve the exam?

Each of these questions suggests a comparison. Sometimes when you analyze data, you will need to compare scores within a sample (are you abnormal or deviant?) or across variables (as good in French as Physics). To do so effectively, you will need to present the comparisons in a way that facilitates decision making. You may be asked:

• What percentage of people falls below a given score?
• What is the relative standing of a score in one distribution versus another?
• What score or scores can be used to define an extreme or deviant situation?

You can do all of these with the Z-Score!