Deletion or selection of items from a test for an analysis, but without removing the responses from your data file, is easily accomplished by creating a file in which each line contains the sequence number or numbers of items to be deleted or selected. Specify this file by means of the control variable, IDFILE=, or enter the deletion list in the control file using IDFILE=*. Your control file should include item labels for all items, including the ones you are deleting. It has the same functionality as IDELETE=. ISELECT= is another way of deleting items. IDFILE= can be action from the Specification menu dialog box.

 

 

a) Delete an item: enter the item number. E.g., to delete item 5, enter

 5

 

b) Delete a range of items: enter the starting and ending item number on the same line separated by a blank or dash. E.g., to delete items 13 through 24

 13-24

or

 13 24

 

c) Select an item for analysis: enter a plus sign then the number.

E.g., to select item 19 from a previously deleted range

 +19

 

d) Select a range of items for analysis: enter a plus sign, the starting number, a blank or dash, then the ending number. E.g., to select items 17 through 22

 +17-22

or

 +17 22

 

e) If a + selection is the first entry in the deletion file, then all items are deleted before the first selection is undertaken, so that the items analyzed will be limited to those selected, e.g,

if +10-20 is the only line in the item deletion file for a 250 item test, it means

 1-250  ; delete all 250 items

 +10-20 ; reinstate items 10 through 20.

 

f) You may specify an item deletion list in your control with

 IDFILE=*

 (List)

 *

e.g.,

 IDFILE=*

 17  ; delete item 17

 2  ; delete item 2

 *

 

Example 1: You wish to delete the fifth and tenth through seventeenth items from an analysis, but then keep item fourteen.

1. Create a file named, say, ITEM.DEL

  2. Enter into the file, the lines:

 5

10-17

 +14

 

3. Specify, in the control file,

   NI=50

   ITEM1=63

   IDFILE=ITEM.DEL

   TABLES=1110111

   &END

 

 or, specify in the control file,

   NI=50

   ITEM1=63

   IDFILE=*

   5

   10-17

   +14

   *

   TABLES=1110111

   &END

 

Example 2: The analyst wants to delete the most misfitting items reported in Table 10.

1. Set up a standard control file.

2. Specify

IDFILE=*

*

3. Copy the target portion of Table 10.

4. Paste it between the "*"

5. Delete characters before the entry numbers.

6. Type ; after the entry numbers to make further numbers into comments.

 

TITLE = 'Example of item deletion list from Table 10'

IDFILE = *

Delete the border character before the entry number

; ENTRY   RAW                            INFIT     OUTFIT             

;   NUM  SCORE  COUNT  MEASURE  ERROR MNSQ  ZSTD MNSQ  ZSTD PTBSE  ACTS                            G  

      5 ; 2     4      .00     1.03 1.48   1.8 1.50   1.8 A-.83  FIND BOTTLES AND CANS           0  

      8 ; 2     4      .00     1.03 1.40   1.6 1.43   1.6 B-.71  LOOK IN SIDEWALK CRACKS         0  

      4 ; 3     4      .00      .62 1.33    .7 1.49    .9 C-.21  WATCH GRASS CHANGE              0  

      9 ; 4     4      .00      .74 1.51    .8 1.57    .9 D-.59  LEARN WEED NAMES                0  

     20 ; 1     4      .00     1.03 1.12    .5 1.14    .6 E-.05  WATCH BUGS                      0  

     24 ; 6     4      .30     1.03 1.15    .6 1.13    .5 F-.15  FIND OUT WHAT FLOWERS LIVE ON   0

Enter the ; to make details to right of entry numbers into comments

*

 

Example 3: The analyst want to delete item 4 and items 18 to 23 on the DOS control (or Extra Specifications) line:

Extra specifications? IDFILE=* 4 18-23 * (Enter)

or

C:>WINSTEPS CONTROL.FIL OUTPUT.FIL IDFILE=* 4 18-23 *