SDFILE= item structure deletion file

This is better performed with IREFER= and IVALUE=. SDFILE= is not supported in this version of Winsteps.

Deletion of categories from a test analysis (i.e. conversion of responses in these categories to "missing data"), but without removing these responses from your data file, is easily accomplished by creating a file in which each line contains the number of the category to be deleted from that item and its grouping. If there is more than one grouping, the sequence number of an item representing a grouping followed by a blank.

Specify this file by means of the control variable, SDFILE=, or this information may be specified in the control file using SDFILE=*.

Since rating (or partial credit) scales may be shared by groupings of items, deletion of categories is performed by grouping:

a) If no ISGROUPS= control variable is specified, no item need be entered, since specifying deletion of a category deletes that category for all items.

b) If a ISGROUPS= control variables is specified, then specifying deletion of a category for one item deletes that category for all items in the same grouping.

c) If ISGROUPS=0 is specified, only the specified category for the specified item is deleted.

Example:        You wish to delete particular categories for the fifth and tenth "partial credit" items for this analysis.

1. Create a file named, say, "CAT.DEL"

2. Enter into the file, the lines:

       5 3 (item 5 category 3)

       10 2 (item 10 category 2)

3. Specify, in the control file,

       SDFILE=CAT.DEL

       ISGROUPS=0

or, enter in the control file,

       SDFILE=*

               5 3

               10 2

               *

       ISGROUPS=0