DTC Quantitative Methods Summary of some SPSS commands Weeks 1 & 2, January 2012

FILE / OPEN / DATA can be used to read in an existing data file (SPSS system file) VIEW / VALUE LABELS can be used to switch between numerical values and their attached value labels in the data editor/data window UTILITIES / VARIABLES can be used to examine the information for specific variables (e.g. the match between values (category codes) and value labels) WINDOW can be used to switch between open windows (e.g. the data editor/data window and the output window) Some basic menu choices

Entering, editing and saving A bit of output such as a cross-tabulation can be edited within the output window by double-clicking upon it, and then double-clicking on the bit of the cross-tabulation that is to be changed (e.g. the labelling of rows and columns, the table’s heading, etc.) When entering new data, data can be typed into the rows (cases) and columns (variables) of the data editor, and variable names, variable & value labels, missing value codes, etc., can be added by clicking on “Variable View” and amending the relevant entries in the rows corresponding to each variable FILE / SAVE AS can be used to save the contents of the output window, or an amended version of the data file, depending on which window is on display

Some basic descriptive statistics ANALYZE / DESCRIPTIVE STATISTICS / FREQUENCIES can be used to show how the cases are distributed across the categories (values) of a variable, in terms of frequencies, percentages and cumulative percentages. The CHARTS sub-menu within ANALYZE / DESCRIPTIVE STATISTICS / FREQUENCIES can be used to display data in the form of pie-charts/bar charts/histograms, and the charts produced can be edited by double-clicking on them (e.g. to alter the range of values displayed) ANALYZE / DESCRIPTIVE STATISTICS / CROSSTABS can be used to cross- tabulate two categorical variables, and the CELLS sub-menu can be used to provide row/column/total percentages GRAPHS / LEGACY DIALOGS / LINE / MULTIPLE can be used to look at how differences between groups in rates vary with age, time, etc.

Weighting DATA / WEIGHT CASES can be used to weight datasets to compensate for the effects on representativeness of disproportionate sampling,, etc. The facility can also be used to ‘weight’ each row of the data window (i.e. count each case a specified number of times), with the weights being obtained from one of the columns (variables) in the data window. This facility can be used to facilitate the entry of existing cross-tabulations into the data window, with two columns (variables) being set up to contain the different combinations of row and column numbers for the cross- tabulation, and a third column (variable) being set up to contain the number of responses in that row and column (i.e. the ‘weights’).

Recoding and computing TRANSFORM / RECODE INTO DIFFERENT VARIABLES can be used to add together (aggregate) or remove some of the categories of a variable so that it can be used in a less detailed form; the relationship between the values of the old and new versions of the variable is specified within the OLD AND NEW VALUES sub-menu, and the new version is a separate variable which can be given a new name, be assigned value labels via “Variable View”, etc. TRANSFORM / COMPUTE VARIABLE can be used to generate new variables in a variety of ways by manipulating and/or combining one or more existing variables. For example, a variable can be transformed (e.g. age can be turned into age-squared), or a number of items (variables) can be combined to produce an index/‘scale’.