A Review of SPSS

by Maureen Allen, MPH, RN-C

allen@healthguide.com

 

When I reviewed SPSS 7.0 last year, I was impressed with the multiple new features that made the program much more user friendly. Helpful additions included the easy-to-use interface, understandable navigation and output. The new version, SPSS 8.0, is even easier to use with additional tools such as pivot table, interactive tables, and Results Coach.


Though SPSS 8.0 uses slightly more hard disk space than SPSS 7.0, the specifications for the computer have not changed; a 486/50 or higher, 16 MB of RAM, a math co-processor, and Windows 95 or Windows NT 4.0 are recommended. This reviewer tested the software on a Pentium 200, 64 MB RAM with Windows 98. Using the CD-ROM to install the software is easy as long as users follow the attached directions for entering the pass codes. The software runs the statistics quickly, often taking less than a second to complete most statistical procedures.


The Open Database Connectivity (ODBC) query has improved since the last version. It has the ability to import Office 97 Excel files as well as Access 97, dBase, FoxPro, Paradox, and text files. Multiple Excel worksheets can be imported by dragging and dropping to the include box which is on the right side of the window. Then, SPSS will ask for the relationship between the worksheets and an arrow is drawn between related tables. When importing, SPSS also allows for the user to specify or limit the data. This is an improvement because now the multiple worksheet function of Excel is not hindered.


For text data, SPSS has included a helpful window to guide you through the process. The query can be saved as a file and run at later time. This is great if the primary data is being kept in a spreadsheet, database, or text file. Variable names now show the data type with an icon beside the variable name. By a right click of the mouse, information can be obtained including the variable name, data type, and data labels. Unfortunately, variable names are still limited to eight characters but data labels can now be as long as 255 characters. Variable labels can be used to enter data by double clicking and choosing from a list. The data type for each variable is defined by the values in the first row of the spreadsheet. If the user wants to change the data definition, is simply done using the data menu.


The data editor has the same basic data structure. SPSS is not a spreadsheet, so formulas to calculate or transform variables can not be entered in the basic structure. If the original data file is a spreadsheet with variables that were calculated using formulas, these variables will not be imported. Variables in SPSS can be changed. The formula to make this change is not saved within the data structure of the table as it is with a spreadsheet. New variables are placed in the last row of the table.


Other improvements and enhancements have been made to some of statistical analyses, such as crosstabs. Now both the observed and expected values can be obtained for each cell as well as information on residuals, percentages and column totals. Similar improvements have been made to the ANOVA procedure.


SPSS 8.0 has also made customizing tables easier. The program has a list of different templates and styles. Fonts and attributes can easily be changed. However, the statistics are not recalculated if any numbers are changed; any changes that need to be made should be done in the basic data table. Footnotes can also be added. Tables can even be scaled to fit a page or slide, which is great for presentations.


Pivot tables are new to SPSS. Pivoting works with both tables and charts and allows the user to view the data from different perspectives. This feature allows you to easily switch the rows and columns (i.e., rows become columns and columns become rows). It is easy; all the user needs to do is drag and drop. The order of the variables is essential in creating a pivot table. The icons in the pivot table replicate the order of the elements within the original table. Pivot Tables also can be used to create, expand, or collapse layers within a table or chart, an important feature when trying to simplify data for publishing. Sometimes data is better explained in another type of chart. A pivot table enables the user to determine which chart demonstrates the best explanation of the data.


Another advantage of SPSS 8.0 is the ability to copy output to another application as a metafile. The metafile can be inserted into the other program as a picture, therefore taking less space and enabling the word processor to redraw the image more rapidly when editing the document. If you do not want to use a metafile approach, output can also be copied as unformatted text. SPSS places tabs between the columns which can be adjusted in the word processing application.


Even the help section of SPSS 8.0 has been expanded to assist new users. Clicking the right button of the mouse defines a term in a popup window. The Statistical Coach prompts the user with simple questions about whether he or she wants to summarize, describe or present data. It further probes for whether the person wants to look at a distribution, dispersion, or simply compare groups for significant differences. The Coach also queries the user about whether he/she wants to identify a relationship between variables of groups of similar cases, then directs the user to the most appropriate statistic. However, it is not foolproof and the user needs to know something about the analysis he/she needs.


In addition to the Statistical Coach, SPSS has a Results Coach, which can explain the elements of the table and specify the role of the elements in assessing report findings. It does this by using popup screens with one or two brief statements. It does not tell the user what to write or interpret but helps the user better understand how the different elements are being utilized within the table.


The Tutorial has been enhanced and includes general health, sales, and survey data for the user to try the different features of SPSS. The SPSS texts use these data sets to explain concepts and methodology. The Online Tutorial provides an overview of many of the features of SPSS. It is a brief overview of some of the features of SPSS.


The basic package still covers most of the statistics that the majority of users need, though the price is expensive for the casual user. SPSS does have a student version, which limits the number of entries that can be made in the basic table but is essentially the same program. Most universities have licensing agreements with SPSS which may lower the price for some users. SPSS is currently available for the following platforms: Windows 95 or higher, Windows NT 4.0, Mac, and OS2.


This reviewer found the program easier to use than previous versions of SPSS. Some sections of the software are the same, which is good news for experienced users who wish to check the underlying code to ensure that the correct statistic was run. With its range of new features and understandable interface, SPSS 8.0 is useful to everyone, from the novice to the most experienced statistician.