How to combine categorical variables in spss

Summarize variables in SPSS and select SPSS cases

Before data can be evaluated with SPSS, it usually has to be processed first. This step often causes difficulties for many users and wastes an unnecessary amount of time. In this article, we therefore show how two important work steps in data preparation can be carried out quickly and easily: Summarizing variables in SPSS (using the Calculate variables Command) and select in SPSS cases.

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This article answers the following questions:

  • How can one summarize variables in SPSS?
  • How do you use the Calculate variables Function in SPSS to calculate scale mean values?
  • Which method can be used to select in SPSS cases?

Summarize variables in SPSS: Many variables become one!

During data preparation, for example in order to be able to evaluate a questionnaire, it is often necessary to combine several variables into a single one. This is especially true for data from questionnaires: Surveys often contain different questions about a construct (e.g. several questions about employee satisfaction). Before the actual analysis, these answers must then be summarized into a single variable. If you want to summarize variables in SPSS, you should usually use the mean value of the variables. The average value for all answers is also called the scale mean. In order to summarize several variables using the mean, however, the individual variables should all be scaled equally (e.g. a Likert scale from 1 to 5).

Occasionally it is also necessary to group variables with different scales. In that case, however, the variables should first be uniformly scaled using a transformation. This can be achieved, for example, by a z-transformation.

Do you need help transforming your data? Or do you need support with other aspects of your SPSS evaluation? Our experts will be happy to assist you with professional SPSS help!

Summarize Variables (SPSS): Example of employee satisfaction

The enterprise Happy Workers GmbH conducted a survey on various aspects of employee satisfaction. Among other things, the variable Satisfaction with job and work situation measured. The employees have 8 questions on a Likert scale of 1 (does not apply) until 5 (true) answered.

Descriptive statistics for the individual items

A reliability analysis with Cronbach's Alpha was already carried out during the data preparation. This confirms that the items are internally consistent. These 8 questions are now to be combined into one variable using a scale mean. If you want to summarize variables in SPSS, select the menu item in SPSS TransformCalculate variables.

Summarizing variables in SPSS: The menu for Calculate variables

Under Target variable you can now enter the name of the new variable (e.g. Zuf_APlatz). In addition to the name, it is advisable to enter a label for the new variable. The label can describe the variable more precisely. The variable can be labeled using the button Type & lettering ... specify (e.g. Satisfaction with job and work situation).

Calculating variables in SPSS: Labels make data management easier

Under Numerical expression you can now specify how the summary variable should be calculated. The function can be used to calculate the mean value. For our example, the scale mean can be calculated as follows:

Or shorter:

In this variant, the average for all variables is betweenZuf_APlatz1 andZuf_APlatz8 calculated. The sequence of the variables in SPSS is decisive! For this, the items in the variable list in SPSS must be sorted in such a way that they are between Zuf_APlatz1 and Zuf_APlatz8 stand.

There is one more problem with this formula: it only includes cases that really are all Have answered 8 items. This is often a bit too strict. As a tried and tested compromise, we recommend using all cases that answered at least 66% of all items. So for our example we want to include all cases that answered at least 6 out of 8 questions. In SPSS we can achieve this with the function:

The Calculate Variables option can be used to calculate scale mean values

With one click on OK the new variable is then calculated. This summary variable can now be used for further analysis.

Select cases in SPSS: Limit analysis to specific cases

In many cases it makes sense to exclude parts of the data from the analysis. This is often the case, for example, if outliers were identified via an SPSS box plot. It may then be necessary to exclude these outliers from further analysis. But in other cases too, you may occasionally only want to select certain cases for the analysis. For example, sometimes we are only interested in the results for certain subgroups in the data. In the following example we will discuss such a case.

Select cases (SPSS): Example of employee satisfaction

In the last step, the scale mean for the Satisfaction with job and work situation calculatedNow she wants Happy Workers GmbH I would like to know what the situation is about satisfaction, especially for employees in accounting with a university degree. Accounting staff have to pay for the variable Department the value “3”. Employees with university degrees have for the variable education the value “2”. If you want to select in SPSS cases, you choose the menu item DataSelect cases.

Select cases (SPSS): Menu

The SPSS Select Cases menu opens. To filter cases, select the option "If condition applies". To determine which cases should be selected, press the button "If... ”. Here you can now define the conditions for the cases.

For our example we want to select cases in SPSS that have a value of “3” for Department have (accounting).

At the same time, the employees should also have a value of “2” for education have (university degree). We can define such AND conditions with the “&” sign:

Menu for selecting cases in SPSS

With a click on OK, all cases that do not meet our criteria will be sorted out.

Cases that are not selected are crossed out in SPSS

For the data analysis, SPSS then only uses the selected cases.

Descriptive statistics for the selected cases

Summarize variables in SPSS and select cases for successful data preparation

In this article we showed how to quickly summarize variables in SPSS. It also explained how easy it is to choose in SPSS cases. Both work steps are carried out extremely frequently during data preparation. Anyone who can safely master these processes in SPSS can therefore save valuable time. We hope that this will provide understandable help for data preparation. Do you have further questions about data preparation or data analysis in SPSS? Contact our experts for professional support for your SPSS evaluation.

Keywords: data preparation, selecting SPSS cases, summarizing SPSS variables, calculating variables