CATREF= reference category for Table 2 = (item measure)

If a particular category corresponds to a criterion level of performance, choose that category for CATREF=.

 

Table 2, "most probable responses/scores", maps the items vertically and the most probable responses, expected scores, and Rasch-Thurstonian thresholds (50% cumulative probabilities) horizontally. Generally, the vertical ordering is item difficulty measure. If, instead, a particular category is to be used as the reference for sorting, give its value as scored and recoded.

 

Special uses of CATREF= are:

CATREF=-3 for item entry order

CATREF=-2 for item measure order

CATREF=-1 for items measure order with ISGROUPS=

CATREF=0 for item measure order

CATREF=1 ... 32767 for item measure order based on this category.

 

Example 1: You have 4-point partial-credit items, entered in your data as A,B,C,D, and then scored as 1,2,3,4. You wish to list them based on the challenge of category C, rescored as 3,

  CODES =ABCD  ; original responses

  NEWSCORE=1234 ; rescored values

  RESCORE=2  ; rescore all

 

  CATREF=3  ; Table 2 reference category

  ISGROUPS=0  ; partial credit: one item per grouping

If, for an item, the category value "3" is eliminated from the analysis or is the bottom category, the nearest higher category is used for that item.

 

Example 2: You have 6 3-category items in Grouping 1, and 8 4-category items in Grouping 2. You wish to list them in Table 2.2 by measure within grouping, and then by measure overall.

  CODES=1234

  NI= 14

  ISGROUPS= 11111122222222

  TFILE=*

  2.2 0 0 0 -1  -1 ; means CATREF=-1

  2.2 0 0 0 0  ; last 0 means CATREF=0

  *