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The MDS Procedure |
The MDS procedure generally produces results similar to those from the ALSCAL procedure (Young, Lewyckyj, and Takane 1986; Young 1982) if you use the following options in PROC MDS:
Unlike PROC ALSCAL, PROC MDS produces no plots, so you must use output data sets and PROC PLOT or PROC GPLOT.
The MDS and ALSCAL procedures may sometimes produce different results for the following reasons:
PROC MDS accepts some PROC ALSCAL options as synonyms for the preceding options, as displayed in Table 40.1.
Table 40.1: PROC MDS Options Compared to PROC ALSCAL OptionsAccepted by | Related PROC MDS Option | |
PROC ALSCAL Option | PROC MDS? | or Comments |
CONDITION= | Yes | |
CONVERGE= | Yes | Convergence measures are |
not comparable | ||
CUTOFF= | Yes | |
DATA= | Yes | |
DEGREE= | No | |
DIMENS= | Yes | |
DIRECTIONS= | No | |
HEADER | Yes | Default in PROC MDS |
IN= | Yes | |
ITER= | Yes | MAXITER= |
LEVEL= | Yes | LEVEL=NOMINAL is not |
supported | ||
MAXDIM=m | Yes | DIMENSION=n TO m |
MINDIM=n | Yes | DIMENSION=n TO m |
MINSTRESS= | Yes | MINCRIT= |
MODEL=EUCLID | Yes | COEF=IDENTITY |
MODEL=INDSCAL | Yes | COEF=DIAGONAL |
MODEL=GEMSCAL | No | |
MODEL=ASYMSCAL | No | |
MODEL=ASYMINDS | No | |
NEGATIVE | (Yes) | In PROC MDS, the NEGATIVE |
option affects slopes and powers, | ||
not subject weights. | ||
NOULB | Yes | |
OUT= | Yes | Some differences in contents |
PLOT | No | |
PLOTALL | No | |
No | ||
READV, etc. | No | Use WHERE data set option |
READFIXV, etc. | No | |
ROWS= | No | |
SHAPE=SYMMETRI | Yes | SHAPE=TRIANGLE |
SHAPE=ASYMMETR | Yes | SHAPE=SQUARE |
SHAPE=RECTANGU | No | Use SHAPE=TRIANGLE with |
extra missing values to | ||
fill out the matrix. | ||
SIMILAR | Yes | |
TIESTORE= | Yes | Ignored by PROC MDS |
UNTIE | Yes |
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