Missing Data

In cases where there is no data available for some variables, then those cells in the spreadsheet are displayed as blanks. Those missing data are marked in the spreadsheet by a reserved value (by default it is -999999998; this value can be changed separately for each variable in the Current Specs dialog box and viewed in the spreadsheet toolbar Show Field when a blank cell is highlighted in the spreadsheet). Values of a variable that are assigned such missing data codes are ignored in all analyses (i.e., either Pairwise MD Deleted, or Casewise MD Deleted is used). See also, Casewise vs. pairwise deletion of missing data.

Alternatively, you can use mean substitution of missing data (replacing all missing data in a variable by the mean of that variable) in order to eliminate missing data in the data file. This way of handling missing data can be specified in many modules; you can also use this method to permanently "remove" the missing data from your data set. For more information on the advantages and disadvantages of mean substitution, see Pairwise Deletion of Missing Data vs. Mean Substitution.