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The parameter represents the item location which, in the case of attainment testing, is referred to as the item difficulty. It is the point on θ {\displaystyle {\theta }} where the IRF has its maximum slope, and where the value is half-way between the minimum value of c i {\displaystyle c_{i}} and the maximum value of 1.
The item-total correlation provides an index of the discrimination or differentiating power of the item, and is typically referred to as item discrimination. In addition, these statistics are calculated for each response of the oft-used multiple choice item, which are used to evaluate items and diagnose possible issues, such as a confusing ...
The Rasch model, named after Georg Rasch, is a psychometric model for analyzing categorical data, such as answers to questions on a reading assessment or questionnaire responses, as a function of the trade-off between the respondent's abilities, attitudes, or personality traits, and the item difficulty.
Difficulty level of the items (p), is assumed to be the same for each item, however, in practice, KR-21 can be applied by finding the average item difficulty across the entirety of the test. KR-21 tends to be a more conservative estimate of reliability than KR-20, which in turn is a more conservative estimate than Cronbach's α .
An example of the CPCs for an item with five categories, scored from 0 to 4, is shown in Figure 1. Figure 1: Rasch category probability curves for an item with five ordered categories. A given threshold partitions the continuum into regions above and below its location. The threshold corresponds with the location on a latent continuum at which ...
Last updated Dec. 19. Learn more about homebuying difficulty in most U.S. counties based on factors such as affordability, available homes, homebuying competition and economic stability.
The process of item analysis varies depending on the psychometric model. For example, classical test theory or the Rasch model call for different procedures. In all cases, however, the purpose of item analysis is to produce a relatively short list of items (that is, questions to be included in an interview or questionnaire) that constitute a ...
The Home Buyer Index in Franklin County, Ohio, where Columbus is primarily located, shows difficulty has increased steadily since the beginning of 2020, rising from 39.5 in December 2020 to 74.0 ...