Introduction to Measurement - pages 112-118 and 121-140
3 important questions on Introduction to Measurement - pages 112-118 and 121-140
1.Observed score = True ability + random error + systematic error
Random error = a component or part of the value of a measure that varies entirely by chance. Random error adds noise to a measure and obscures the true value.
Systematic error = a component of an observed score that consistently affects the responses in the distribution.
Cronbach’s alpha
Cronbach’s coefficient alpha is an internal consistency estimate of scale reliability that is mathematically equivalent to all possible split half estimates of reliability.
Cronbach's alpha is a measure of internal consistency, that is, how closely related a set of items are as a group. It is considered to be a measure of scale reliability. A “high” value for alpha does not imply that the measure is unidimensional.
Consequential validity (Messicks concept)
Consequential validity bring attention to the fact that there are personal and social consequences of test scores.
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