Winsteps may not be able to provide an estimate of a measure. INESTIMABLE is reported if all observations are eliminated as forming part of extreme response strings. To make such measures estimable, further data (real or artificial) or Winsteps specifications are required.

 

Example: ISGROUPS=0 is specified (partial credit model) but all responses are in the same category. Winsteps cannot construct a rating scale structure. If possible, include this item in the same ISGROUPS= grouping as an estimable item.