SPSS® 12.0 Command Syntax Reference

1668 WLS
DELTA Subcommand
DELTA, alias POWER, is used in conjunction with the SOURCE subcommand to compute
weights. DELTA specifies the values to use in computing weights. The weights are equal to
1/(SOURCE raised to the DELTA power).
• The specification on DELTA is a list of possible delta values and/or value grids.
• Multiple values and grids can be specified on one DELTA subcommand.
• Delta values can be any value in the range of –6.5 to +7.5. Values below this range are
assigned the minimum (–6.5), and values above are assigned the maximum (7.5).
• A grid is specified by naming the starting value, the keyword TO, an ending value, the
keyword BY, and an increment value. Alternatively, the keyword BY and the increment
value can be specified after the starting value.
• More than one DELTA subcommand can be specified; each subcommand will be executed.
• If DELTA is not specified, the delta value defaults to 1.0.
Example
WLS X1 WITH Y1 Z1
/SOURCE=Z1
/DELTA=0.5.
• In this example, weights are calculated using the source variable Z1 and a delta value of
0.5. Thus, the weights are 1/(SQRT (Z1)).
Example
WLS SHARES WITH PRICE
/DELTA=0.5 TO 2.5 BY 0.5.
• In this example, several regression equations will be fit, one for each value of delta.
• Weights are calculated using the source variable PRICE (the default).
• The delta values start at 0.5 and go up to 2.5, incrementing by 0.5. This specification is
equivalent to 0.5 BY 0.5 TO 2.5.
• The weights that maximize the log-likelihood function will be saved as variable WGT#1.
WEIGHT Subcommand
WEIGHT specifies the variable containing the weights to be used in weighting the cases.
WEIGHT is an alternative to computing the weights using the SOURCE and DELTA subcommands.
If a variable containing weights is specified, the output includes the regression coefficients,
log-likelihood function, and summary regression statistics such as R, R , adjusted
2
R 2
, standard errors, analysis of variance, and t tests of the coefficients. Since no new weights
are computed, no new variable is created. For a description of the output when weights are
calculated by WLS, see “Basic Specification” on p. 1666.
• The only specification on WEIGHT is the name of the variable containing the weights.
Typically, WGT variables from previous WLS procedures are used.
• Only one variable can be specified.