Introduction to SPSS Edward A. Greenberg, PhD ASU HEALTH SOLUTIONS DATA LAB January 7, 2013

Files for this workshop Files can be downloaded from: http://www.public.asu.edu/~eagle/spss or (with less typing): http://tinyurl.com/aa8crpn

SPSS Overview SPSS Statistics is a software package used for statistical analysis. It is now officially named "IBM SPSS Statistics". SPSS uses a graphical user interface. Most operations are “point and click”.

Availability of SPSS Installed on most Health Solutions faculty and staff computers Available via MyApps for installation on faculty, staff and student computers via University site license Run in ASU Online Applications environment (Citrix) via MyApps ASU Computing Sites on all campuses

Basic Steps in Data Analysis Get your data into SPSS Statistics SPSS can read data from a variety of sources. Prepare your data set for analysis Set variable attributes, clean your data and apply any needed transformations. Select a procedure Select a procedure from the menus to calculate statistics or to create a chart. Select the variables for the analysis The variables in the data file are displayed in a dialog box for the procedure. Run the procedure and look at the results Results are displayed in the Viewer.

Getting Data into SPSS Statistics Open a previously saved SPSS Statistics data file Read another type of file Spreadsheet Database Text data file Enter your data directly in the SPSS Data Editor

SPSS Data Files The SPSS Data Editor window has two views. Data View shows a spreadsheet of cases (rows) and variables (columns). Variable View displays the metadata dictionary, where each row represents a variable and shows the variable name, type, and other attributes.

SPSS Data Editor Data View

SPSS Data Editor Variable View

Variable Attributes ATTRIBUTE DESCRIPTION Name Variable name Type Data type Width Number of digits or characters Decimals Number of decimal places Label Descriptive variable label Values Descriptive value labels Missing User‐defined missing values Columns Column width Align Alignment Measure Measurement level Role Role assignment

Variable Attributes VARIABLE NAME Variable names must be unique. Variable names may be up to 64 characters in length. Names can contain letters, numbers, or special characters. Names must start with a letter or @, #, or $.

Variable Attributes DATA TYPE Numeric String 40 character maximum length Integers or numbers with decimals Dates and times (various formats) Other variations of numeric (currency, comma, scientific notation, etc.) String 32,767 maximum length Can contain any characters

Variable Attributes VARIABLE WIDTH For numeric variables, the width of the number that is displayed. String variables can be up to 32,767 characters long.

Variable Attributes DECIMALS Number of decimal places displayed for numeric variables Allowable values are 0 thru (width-1)

Variable Attributes VARIABLE LABEL A descriptive label for a variable Up to 255 characters in length Variable labels can contain spaces and reserved characters that are not allowed in variable names.

Variable Attributes VALUE LABELS You can assign descriptive labels for each value of a variable Particularly useful if your data file uses numeric codes to represent non-numeric categories (for example, codes of 1 and 2 for male and female) Value labels can be up to 120 characters.

Variable Attributes MISSING VALUES Allows you to distinguish between data that are missing for different reasons. You can specify up to three discrete (individual) missing values, a range of missing values, or a range plus one discrete value. Missing values are excluded from most calculations. By default, an empty cell for a numeric variable is treated as missing.

Variable Attributes COLUMN WIDTH The display width of a variable in the Data Editor Affects only the display of values in the Data Editor Does not change the defined width of a variable. Column widths can also be changed in Data View by clicking and dragging the column borders.

Variable Attributes ALIGNMENT Controls the display of data values and/or value labels in Data View The default alignment is right for numeric variables and left for string variables. This setting affects only the display in Data View.

Variable Attributes LEVEL OF MEASUREMENT LEVEL DESCRIPTION Nominal Values represent categories with no intrinsic ranking. Ordinal Values represent categories with some intrinsic ranking. Scale Values represent ordered categories with a meaningful metric, so that distance comparisons between values are appropriate.

Variable Attributes ROLE Some dialogs support predefined roles that can be used to pre-select variables for analysis. Roles include Input (the default), Target, Both, None and several others.

Data Transformations The Transform menu includes routines which perform transformations on selected variables. These include the following, among others: TRANSFORMATION DESCRIPTION COMPUTE Compute values for a variable based on numeric transformations of other variables COUNT Creates a numeric variable that, for each case, counts the occurrences of the same value (or list of values) across a list of variables RECODE Allows you to reassign the values of existing variables or collapse ranges of existing values into new values for a new or existing variable

Running Procedures Most procedures are accessed via the Analyze menu. Procedures are grouped according to type, e.g., Reports, Descriptive Statistics, Compare Means, Tables, General Linear Model, and so on.

Running Procedures Dialog boxes for statistical procedures and charts typically have two basic components: Source variable list A list of variables in the active dataset. Only variable types that are allowed by the selected procedure are displayed in the source list. Target variable list(s) One or more lists indicating the variables that you have chosen for the analysis, such as dependent and independent variable lists.

Results are displayed in the Viewer SPSS Viewer Results are displayed in the Viewer

SPSS Help and Other Resources SPSS Help Menu

SPSS Help and Other Resources Tutorial videos (in Flash format) are available from Central Michigan University at http://calcnet.mth.cmich.edu/org/spss/toc.htm Raynald Levesque maintains an excellent SPSS‐related web site with many helpful resources at http://www.spsstools.net/ The CONHI Data Lab can help you with SPSS: NHI1 391, CONHISTAT@ASU.EDU, (602) 496‐DATA* Many excellent books are available on SPSS * Email probably is the best way to reach us