CWEIGHT Subcommand (LOGLINEAR command)

CWEIGHT specifies cell weights, such as structural zeros, for a model. By default, cell weights are equal to 1.

  • The specification is either one numeric variable or a matrix of weights enclosed in parentheses.
  • If a matrix of weights is specified, the matrix must contain the same number of elements as the product of the levels of the categorical variables. An asterisk can be used to signify repetitions of the same value.
  • If weights are specified for a multiple-factor model, the index value of the rightmost factor increments the most rapidly.
  • If a numeric variable is specified, only one CWEIGHT subcommand can be used on LOGLINEAR.
  • To use multiple cell weights on the same LOGLINEAR command, specify all weights in matrix format. Each matrix must be specified on a separate CWEIGHT subcommand, and each CWEIGHT specification remains in effect until explicitly overridden by another CWEIGHT subcommand.
  • CWEIGHT can be used to impose structural, or a priori, zeros on the model. This feature is useful in the analysis of symmetric tables.

Example

COMPUTE  CWT=1.
IF (HUSED EQ WIFED) CWT=0.
LOGLINEAR HUSED WIFED(1,4) WITH DISTANCE
  /CWEIGHT=CWT
  /DESIGN=HUSED WIFED DISTANCE.
  • COMPUTE initially assigns CWT the value 1 for all cases.
  • IF assigns CWT the value 0 when HUSED equals WIFED.
  • CWEIGHT imposes structural zeros on the diagonal of the symmetric crosstabulation. Because a variable name is specified, only one CWEIGHT can be used.

Example

LOGLINEAR  HUSED WIFED(1,4) WITH DISTANCE
  /CWEIGHT=(0, 4*1, 0, 4*1, 0, 4*1, 0)
  /DESIGN=HUSED WIFED DISTANCE
  /CWEIGHT=(16*1)
  /DESIGN=HUSED WIFED DISTANCE.
  • The first CWEIGHT matrix specifies the same values as variable CWT provided in the first example. The specified matrix is as follows:

    0 1 1 1

    1 0 1 1

    1 1 0 1

    1 1 1 0

  • The same matrix can be specified in full as (0 1 1 1 1 0 1 1 1 1 0 1 1 1 1 0).
  • By using the matrix format on CWEIGHT rather than a variable name, a different CWEIGHT subcommand can be used for the second model.