FAQ/mds/example - CBU statistics Wiki

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location: FAQ / mds / example

Here is an example of input for the SPSS procedure found under analyze:scale: multidimensional scaling.

The input are pairs (i,j) of times of one subject to correctly respond to semantic category j immediately after identifying category i. The matrix is asymmetric and contains dissimilarities (the default) as higher RTs suggest more dissimilarity between a pair of stimuli.

stimulus

a

b

c

d

e

f

a

48

56

23

123

45

460

b

78

84

79

210

39

25

c

80

237

200

145

178

127

d

78

160

150

478

256

290

e

65

250

67

312

4

345

f

410

340

312

324

367

367

The code below, which may also be run from the menu, runs the multidimensional scaling procedure specifying a 6x6 asymmetric matrix of user input for six stimuli and the ordinal level of measurement. 

ALSCAL
  VARIABLES= a b c d e f
  /SHAPE=ASYMMETRIC
  /LEVEL=ORDINAL
  /CONDITION=MATRIX
  /MODEL=EUCLID
  /CRITERIA=CONVERGE(.001) STRESSMIN(.005) ITER(30) CUTOFF(0) DIMENS(2,2) .