UMEAN= or UIMEAN= the mean or center of the item difficulties = 0

Assigns your chosen numerical value to the average measure of the non-extreme items, i.e., a criterion-referenced measure. Previous UPMEAN= values are ignored.

UMEAN= and UIMEAN= are the same specification. Anchor values are treated according to UASCALE=

Table 20 gives the UMEAN= and USCALE= values for a conversion that gives the measures a range of 0-100.

Example 1:        You want to recenter the item measures at 10 logits, and so add 10 logits to all reported measures, to avoid reporting negative measures for low achievers:

       UIMEAN = 10

Example 2:        You want to recenter and user-rescale the item measures, so that the range of observable measures goes from 0 to 100.

       Look at Table 20.1. Beneath the Table are shown the requisite values, e.g.,

       UMEAN = 48.3        ; this is the same as UIMEAN=48.3

       USCALE = 9.7

For more examples, and how to compute this by hand, see User-friendly rescaling