## PSPP

Gnu’s PSPP is an free, open-source clone of IBM’s SPSS. It’s like an SPSS free download! Although some users may prefer the command-line syntax, most will take advantage of PSPP’s simple, easy to use graphical user interface (GUI). One of the best aspects of PSPP is that if you know SPSS you already know PSPP. Like SPSS, PSPP has two tabs, one tab listing variables and the other tab showing data.

### PSPP Data View

In the Data View tab each row represents a case (for example, a test subject). Each column represents a variable.

### PSPP Variable View

In the Variable View tab of PSPP, each row represents a variable. All the familiar variable characteristics from SPSS are present, including variable name, type, width, decimals, label, values, missing, column, align, and measure.

### Familiar Menus and Functions

Another great feature of PSPP is that the menus are very similar to those in SPSS. The menus include File, Edit, View, Data, Transform, Analyze, Utilities, Windows, and Help. All the functions of PSPP are easy to find. For example, if you want to recode data, simply click Transform, then Recode into Same Variables…

This opens the familiar Recode into Same Variables and Old and New Values windows. These allow the user to select the variables to change and how to recode those variables.

### Data Analysis

PSPP is capable of many of the same data analyses as SPSS. These include frequencies, descriptives, explore, crosstabs, one sample t-test, independent samples t-test, paired samples t-test, one way ANOVA, bivariate correlation, K-means cluster, factor analysis, reliability, linear regression, chi square, binomial, and ROC curve.

The analyses in PSPP are very similar to SPSS. For example, Frequencies can produce mean, standard deviation, minimum, maximum, standard error, variance, skewness, standard error of the skewness, range, mode, standard error of the kurtosis, median, sum. Frequencies can also produce histograms, pie charts, and frequency tables.

### Output

Again, if you’re familiar with SPSS you’ll feel right at home with PSPP. Here’s the output from Frequencies:

### Charts

Unfortunately PSPP’s chart capabilities are the weak point of this free statistical package. PSPP can create histograms and pie charts through the Frequencies menu. PSPP can also create boxplots through the EXAMINE command. Gnu recommends Gnuplot for more sophisticated charting: http://www.gnuplot.info/

### Files

PSPP uses .sav files to save data, just like SPSS. This means that PSPP and SPSS can easily share data files. PSPP and SPSS also shares .sps syntax files. The syntax is the same for commands that are available in PSPP. As with SPSS, the command line interface can be used instead of the graphical user interface.