VARIABLES Subcommand (PARTIAL CORR command)

VARIABLES requires a correlation list of one or more pairs of variables for which partial correlations are desired and requires a control list of one or more variables that will be used as controls for the variables in the correlation list, followed by optional order values in parentheses.

• The correlation list specifies pairs of variables to be correlated while controlling for the variables in the control list.
• To request a square or lower-triangular matrix, do not use keyword WITH in the correlation list. This specification obtains the partial correlation of every variable with every other variable in the list.
• To request a rectangular matrix, specify a list of correlation variables followed by keyword WITH and a second list of variables. This specification obtains the partial correlation of specific variable pairs. The first variable list defines the rows of the matrix, and the second list defines the columns.
• The control list is specified after keyword BY.
• The correlation between a pair of variables is referred to as a zero-order correlation. Controlling for one variable produces a first-order partial correlation, controlling for two variables produces a second-order partial correlation, and so on.
• To indicate the exact partials that are to be computed, you can specify order values in parentheses following the control list. These values also determine the partial correlation matrix or matrices to be printed. Up to five order values can be specified. Separate each value with at least one space or comma. The default order value is the number of control variables.
• One partial is produced for every unique combination of control variables for each order value.

Obtaining the Partial Correlation for Specific Variable Pairs

PARTIAL CORR 
  VARIABLES = RENT FOOD PUBTRANS WITH TEACHER MANAGER BY NETSALRY(1).

• PARTIAL CORR produces a rectangular matrix. Variables RENT, FOOD, and PUBTRANS form the matrix rows, and variables TEACHER and MANAGER form the columns.

Specifying Order Values

PARTIAL CORR  
  VARIABLES = RENT WITH TEACHER BY NETSALRY, NETPRICE (1).
PARTIAL CORR  
  VARIABLES = RENT WITH TEACHER BY NETSALRY, NETPRICE (2).
PARTIAL CORR  
  VARIABLES = RENT WITH TEACHER BY NETSALRY, NETPRICE (1,2).
PARTIAL CORR  
  VARIABLES = RENT FOOD PUBTRANS BY NETSALRY NETPURSE NETPRICE (1,3).

• The first PARTIAL CORR produces two first-order partials: RENT with TEACHER controlling for NETSALRY, and RENT with TEACHER controlling for NETPRICE.
• The second PARTIAL CORR produces one second-order partial of RENT with TEACHER controlling simultaneously for NETSALRY and NETPRICE.
• The third PARTIAL CORR specifies both sets of partials that were specified by the previous two commands.
• The fourth PARTIAL CORR produces three first-order partials (controlling for NETSALRY, NETPURSE, and NETPRICE individually) and one third-order partial (controlling for all three control variables simultaneously).