Minimum number of matched examinees Just a number set at 10 at least 10

Minimum number of matched examinees just a number set

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Minimum number of matched examinees *Just a number: set at 10 (at least 10 examinees must be in both reference and focal group at each score level to make comparisons) Rescale (1) polytomous items to 0-1, or not (0) *For our purposes, set as 0. Weighting of cases *Coding with 2 in the command file corresponds to weighting conditional difference at a score point by the proportion of focal candidates who are at that score point; Coding with 1 corresponds to weighting conditional difference at a score point by the proportion of reference and focal candidates of the combined sample at that score point; Coding with 0 corresponds to no weighting at all. Here is a working command file: Sample Test: Math Grade 4, Gender DIF analysis *title M004_s1.dat *data file 76784 *76784 examinees 39 *39 items 12 *Column 12 has gender info M *M for males (reference group) F *F for females (focal group) 13 *Item responses start in column 13 (39I1) *39 one-column-long integer variables 10 *Min. N of matched examinees 0 *No rescaling of polytomous items 1 *Differences at score points weighted by the proportion of the combined sample at the score points 4
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To create a good, working command file, you must check your data to be sure of what columns the various pieces of information are in and to know how many examinee data records to read in. The command file should be named in a descriptive way, but NO MORE THAN EIGHT CHARACTERS. For example, M004gen .cmd would refer to a Math 2000 grade 4 Gender analysis, while M004wa .cmd would be Math 2000 grade 4 Race analyses (White v. African- American) and M004wh .cmd would be Math 2000 grade 4 Race analyses (White v. Hispanic). To run a DOS program, the data file must be labeled as filename .DAT. For your own ease of analysis, you should probably continue to be descriptive in naming these files, but the filenames should be no more than eight characters. NOTE: You must modify the data files once you have made them into .DAT files. Using the DOS editor or a text editor program (probably Wordpad as the files might be too big for Notepad) you must insert three lines at the top of the data file. The first line you will enter is the maximum score for each test item. The second line you enter is a sequence of 0-1 “switches” for including or excluding items from the analysis. An example from grade 4 Math Gender analyses is below. The third line you enter is one that corresponds to aggregation of items. For the purpose of many analyses this row should be a line of zeroes. 111111111111111111111111111111111144444 111111111111111111111111111111111111111 000000000000000000000000000000000000000 5050000474 110101101110111001010000101100110111313 5050000502 001000010001100001010110101010010000000 5050000577WM010110010010010000000000000000000012000 9002038068WM111111010111111111001011111001110033243 9002038228WF010000010010010000011000000000000011010 9002038710HF000011111100000000000100000000100112013 9002038827WF100010111100111011100011111110111122213 9002038836WM111111000100100011100010100110111031033 9002039000WF111111101101110111001110111110110142022 From the first line , you see that most items except the last 5 are dichotomously scored (the maximum score is 1); the last 5 are polytomously scored and the maximum is 4. From the second line , the fact that there is a 1 in each column means that every item on the test in included in the DIF analysis. These are the switches that are important is terms of the DIF procedure we are using.
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