1.2. Cases, variables, values and scores

When collecting data, you collect it from something. This something could be people, things, days, etc. and are called the cases. From each case we like to know different things that can vary per case, the things we want to know from each case are called the variables. Each variable can vary, the possible variations are the values. Finally the specific value of a variable for a case is called a score.

A survey for example has as cases people (or respondents) and the questions on the survey can be considered the variables. A small difference between a survey question and a variable, is that the name of the variable is often shorter. The question ‘What is your gender?’ will have as a variable simply ‘Gender’ and the possible variations are Male and Female. My score for the variable gender would be Male.

In Table 1 a classification of types of questions is shown.

Table 1
Types of questions

Type	Description	Example
1	Open questions
1a	Open questions asking for a number	What is your age? ___
1b	Open questions asking for text	What is your name? ____
2	Closed questions
2a	Closed question, single answer	What is your gender? O Male  O Female
2b	Closed question, multiple answer	Which TV series do you watch? □ Got  □ Walk. Dead  □ Southpark □ Other
3	Semi-closed
3a	Semi-closed, single answer	What is your favourite brand? O Nike O Adidas O Puma O Other, please specify:____
3b	Semi-closed, multiple answer	Which brands do you like? □  Nike □  Adidas □  Puma □  Other, please specify:____
4	List of questions on same scale	Please indicate the level you agree or disagree with the following statements. Strongly disagree Disagree Agree Strongly agree I enjoy this book O O O O The book is clear O O O O The layout is nice O O O O The style is good O O O O

If type 4 uses some form of scale for each of its questions (as in the example), then this type is also known as a Likert [1] scale (Likert, 1932). Note that each question from the Likert scale is called a Likert item, the combined set of the questions is then the Likert scale.

Questions with multiple answers (type 2b and 3b) are often not considered as a variable, but a collection of variables. Each option is considered a yes/no question. In the example of the TV shows the multiple answer question, could also have been rephrased using the following four single answer questions:

• Do you watch Got? O Yes O No
• Do you watch Walk. Dead? O Yes O No
• Do you watch Southpark? O Yes O No
• Do you watch Other? O Yes O No

How to enter questions in SPSS can be found in Appendix A.

>>Next section: Measurement levels

References
Likert, R. (1932). A technique for the measurement of attitudes (Vol. 22). New York: The Science Press.

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[1] Pronounced with a short i as in sick, and not as in lie.