Automatic Dropping of Constants

You can tell Stat/Transfer to automatically drop variables that are constant or missing for a selected subset of data.  You select this option by checking the Drop Constants check box in the Variables dialog box and then pressing the Optimize button.


This feature is useful when the part of a data set selected for transfer contains variables with values that are either constant or missing (such as a pregnancy variable when only male subjects are selected or variables in yearly surveys where the same questions do not appear for each year.)


This feature is not likely to be used often, but is extremely valuable when it is needed, since if the data set has a large number of variables, it can be exceedingly tedious to select only the meaningful ones manually.