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SPSS® 12.0 Command Syntax Reference

SPSS® 12.0 Command Syntax Reference

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102 ALSCAL<br />

Operations<br />

• ALSCAL calculates the number of input matrices by dividing the total number of<br />

observations in the data set by the number of rows in each matrix. All matrices must<br />

contain the same number of rows. This number is determined by the settings on SHAPE<br />

and INPUT (if used). For square matrix data, the number of rows in the matrix equals the<br />

number of variables. For rectangular matrix data, it equals the number of rows specified<br />

or implied. For additional information, see the INPUT and SHAPE subcommands below.<br />

• ALSCAL ignores user-missing specifications in all variables in the configuration/weights<br />

file (see the FILE subcommand on p. 105). The system-missing value is converted to 0.<br />

• With split-file data, ALSCAL reads initial or fixed configurations from the<br />

configuration/weights file for each split-file group (see the FILE subcommand on p. 105).<br />

If there is only one initial configuration in the file, ALSCAL rereads these initial or fixed<br />

values for successive split-file groups.<br />

• By default, ALSCAL estimates upper and lower bounds on missing values in the working<br />

data file in order to compute the initial configuration. To prevent this, specify<br />

CRITERIA=NOULB. Missing values are always ignored during the iterative process.<br />

Limitations<br />

Example<br />

• Maximum 100 variables on the VARIABLES subcommand.<br />

• Maximum six dimensions can be scaled.<br />

• ALSCAL does not recognize data weights created by the WEIGHT command.<br />

• ALSCAL analyses can include no more than 32,767 values in each of the input matrices.<br />

Large analyses may require significant computing time.<br />

* Air distances among U.S. cities.<br />

* Data are from Johnson and Wichern (1982), page 563.<br />

DATA LIST<br />

/ATLANTA BOSTON CINCNATI COLUMBUS DALLAS INDNPLIS<br />

LITTROCK LOSANGEL MEMPHIS STLOUIS SPOKANE TAMPA 1-60.<br />

BEGIN DATA<br />

0<br />

1068 0<br />

461 867 0<br />

549 769 107 0<br />

805 1819 943 1050 0<br />

508 941 108 172 882 0<br />

505 1494 618 725 325 562 0<br />

2197 3052 2186 2245 1403 2080 1701 0<br />

366 1355 502 586 464 436 137 1831 0<br />

558 1178 338 409 645 234 353 1848 294 0<br />

2467 2747 2067 2131 1891 1959 1988 1227 2042 1820 0<br />

467 1379 928 985 1077 975 912 2480 779 1016 2821 0<br />

END DATA.<br />

ALSCAL VARIABLES=ATLANTA TO TAMPA<br />

/PLOT.

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