Example 2: Control and anchor files

A control file, EXAM2.TXT, for the analysis of a test containing 18 items, each item already scored dichotomously as 0,1. The person-id data begins in column 1 and the item-response string begins in column 11. The standard tables will be appear in the printout. There is user scaling. Items 2, 4, 6 and 8 are anchored at 400, 450, 550 and 600 units respectively, supplied in file EXAM2IAF.TXT Your data is in file EXAM2DAT.TXT:

; This file is EXAM2.TXT

TITLE='KNOX CUBE TEST - ANCHORED'   ; the title for output

NI=18               ; the number of items

ITEM1=11            ; position of first response in data record

NAME1=1             ; first column of person-id in data record

PERSON=KID

ITEM=TAP

DATA=EXAM2DAT.TXT   ; name of data file

IAFILE=EXAM2IAF.TXT ; this is item anchor (input) file: it is the IFILE= of an earlier analysis

CONVERGE=L          ; use only Logits for convergence criterion

LCONV=.005          ; converged when biggest change is too small to show on any report.

; What follows is equivalent to the IAFILE= above

; IAFILE=*         ; item anchor file list

;2 400             ; item 2 anchored at 400 units

;4 450             ; item 4 anchored at 450 units

;6 550             ; item 6 anchored at 550 units

;8 600             ; item 8 anchored at 600 units

; *

UIMEAN=500          ; user scaling - item mean

USCALE=100          ; user scaling - 1 logit = 100 user units

UDECIM=0            ; print measures without decimals

&END

1-4                  ; item labels, starting with the first item

 .

4-1-3-4-2-1-4

END NAMES            ; End of this file

The anchoring information is contained in file EXAM2IAF.TXT and contains the following lines, starting in column 1:

2 400 ; item 2 anchored at 400 units:

     ; if logits are user-rescaled, then anchor values are also expected to be user-rescaled.

     ; for logit anchor values, specify UASCALE=1

4 450 ; item 4 anchored at 450 units

6 550 ; item 6 anchored at 550 units

8 600 ; item 8 anchored at 600 units

Item calibration files, IFILE=, from prior runs can be used as item anchor files, IAFILE=, of later runs.

Your data is in the separate file, EXAM2DAT.TXT, with person-id starting in column 1, and item responses starting in column 11:

Richard M 111111100000000000

Tracie  F 111111111100000000

  .

Elsie   F 111111111101010000

Helen   F 111000000000000000    End of this file