If you specify the option METHOD=SEQ and do not include a SIZE statement, PROC SURVEYSELECT uses the equal probability version of Chromy's method for sequential random sampling. This method selects ...

If you specify the option METHOD=PPS_SEQ, PROC SURVEYSELECT uses Chromy's method of sequential random sampling. Refer to Chromy (1979) and Williams and Chromy (1980). Chromy's method selects units ...