The PDWEIGHTS statement can be used to specify one to seven daily weights. The statement can only be used with monthly series that are seasonally adjusted using the multiplicative model. These weights are used to compute prior trading-day factors, which are then used to adjust the original series prior to the seasonal adjustment process. Only relative weights are needed; the X11 procedure adjusts the weights so that they sum to 7.0. The weights can also be corrected by the procedure on the basis of estimates of trading-day variation from the input data.

See the section Prior Daily Weights and Trading-Day Regression for details and examples using the PDWEIGHTS statement.

Each day=w option specifies a weight (w) for the named day. The day can be any day, Sunday through Saturday. The day keyword can be the full spelling of the day, or the three-letter abbreviation. For example, SATURDAY=1.0 and SAT=1.0 are both valid. The weights w must be a numeric value between 0.0 and 10.0.

The following is an example of a PDWEIGHTS statement:

   pdweights sun=.2 mon=.9 tue=1 wed=1 thu=1 fri=.8 sat=.3;

Any number of days can be specified with one PDWEIGHTS statement. The default weight value for any day that is not specified is 0. If you do not use a PDWEIGHTS statement, the program computes daily weights if TDREGR=ADJUST is specified. See Shiskin, Young, and Musgrave (1967) for details.