Unanchored persons with extreme (zero, minimum possible or perfect, maximum possible) scores provide no information for estimating item measures, but they are reported and included in summary statistics. To remove them:

 

PDROPEXTREME = No ; do not drop extreme persons (standard)

 

PDROPEXTREME = Yes or All ; drop zero (minimum possible) and perfect (maximum possible) scores

 

PDROPEXTREME = Zero or Low or Bottom or Minimum ; drop zero or minimum-possible scores

 

PDROPEXTREME = Perfect or High or Top or Maximum ; drop perfect or maximum-possible scores

 

Example 1: The data file contains many data records of persons who did not attempt this test and so were scored 0. They are skewing the test statistics:

 PDROPEXTREME = Zero

 

Example 2: On a satisfaction survey, hurried respondents mindlessly code every item "highly satisfied".

 PDROPEXTREME = Perfect