EXTREME PERSON SCORES

            Question:

How does RUMM2030 handle persons with extreme scores?

            Explanation:

There are two important points regarding extreme scores with Rasch analysis using RUMM2030:

• As part of any analysis proper in which item and person estimates are determined, RUMM2030 identifies extreme persons. These are persons with zero scores or 'perfect' scores ON THE ITEMS ATTEMPTED. These persons are retained throughout all analyses and included in many displays where an option to include or exclude such extreme persons is provided.
• Extreme persons are provided with an estimate of their location parameter. These estimates are derived from a geometric mean algorithm which uses, respectively, the three highest person location estimates [for the items attempted] and the three lowest person location estimates [for the zero score].
• For any set of items, each total score has a finite estimate, except for a score of zero or the maximum score 'M'.  The extrapolated score is based on the three finite scores: M - 1, M - 2, and M - 3 [for an extreme score of M], and 1, 2 and 3 [for an extreme minimum score of zero].

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