The MDS Procedure

PROC MDS shares many of the features of the ALSCAL procedure (Young, Lewyckyj, and Takane; 1986; Young; 1982), as well as some features of the MLSCALE procedure (Ramsay; 1986). Both PROC ALSCAL and PROC MLSCALE are no longer a part of SAS; however, they are described in the SUGI Supplemental Library User’s Guide, Version 5 Edition. 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:

• FIT=SQUARED

• FORMULA=1 except for unfolding data, which require FORMULA=2

• PFINAL to get output similar to that from PROC ALSCAL

Running the MDS procedure with certain options generally produces results similar to those from using the MLSCALE procedure (Ramsay; 1986) with other options. This is illustrated with the following statements:

proc mds fit=log level=loginterval ... ;

proc mlscale stvarnce=constant suvarnce=constant ... ;

Alternatively, using the FIT=DISTANCE option in the PROC MDS statement produces results similar to those from specifying the NORMAL option in the PROC MLSCALE statement.