``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69``` ```(Q) I'm trying to generate orders for blocks of trials comprised of 3 types of stimuli (POS, NEG, and NEU), and I need to make sure that there is a roughly equal number of all the permutations of pairs of stimuli represented in a block of trials, say 2-3 of each pair within a block. There are 9 possible pairs of one valence followed by another-- POS followed by NEG, POS followed by NEU, NEG - POS, NEG - NEU, NEU - POS, NEU - NEG, POS - POS, NEG - NEG, and finally NEU - NEU. In a block of 24 trials, there are 23 total pairs. I'm generating random orders, and then I need a way to count the number of pairs represented in those random orders-- anyone know of a way to do this? I've been tallying them by hand-- there must be a better way! *(A) Posted to SPSSX-L by Raynald Levesque on 2002/03/12. DATA LIST free /order (F2) val1 (A3). BEGIN DATA. 1 POS 2 POS 3 POS 4 NEU 5 NEG 6 NEG 7 NEU 8 NEU 9 NEG 10 NEG 11 NEU 12 POS 13 NEG 14 POS 15 NEG 16 NEU 17 NEG 18 POS 19 NEG 20 POS 21 NEU 22 POS 23 NEU 24 NEU END DATA. RECODE val1 (CONVERT) ('POS'=1) ('NEU'=2) ('NEG'=3) INTO v1. SAVE OUTFILE='c:\\temp\\mydata.sav'. *////////////////////. DEFINE !shuffle(fname=!TOKENS(1) /nb=!TOKENS(1)) GET FILE=!fname. !DO !cnt=1 !TO !nb. COMPUTE draw=UNIFORM(1). SORT CASES BY draw. CREATE v2=LEAD(v1,1). COMPUTE pair=v1*10+v2. LIST val1. FREQ VAR=pair. !DOEND !ENDDEFINE. *////////////////////. * Use any arbitrary number as the seed. SET SEED=1987653. * Do 5 shuffles. !shuffle fname='c:\\temp\\mydata.sav' nb=5. ```
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