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Alpha is also a function of the number of items, so shorter scales will often have lower reliability estimates yet still be preferable in many situations because they are lower burden. An alternative way of thinking about internal consistency is that it is the extent to which all of the items of a test measure the same latent variable .
It is a special case of Cronbach's α, computed for dichotomous scores. [2] [3] It is often claimed that a high KR-20 coefficient (e.g., > 0.90) indicates a homogeneous test. However, like Cronbach's α, homogeneity (that is, unidimensionality) is actually an assumption, not a conclusion, of reliability coefficients.
Cronbach's alpha (Cronbach's ), also known as tau-equivalent reliability or coefficient alpha (coefficient ), is a reliability coefficient and a measure of the internal consistency of tests and measures. [1] [2] [3] It was named after the American psychologist Lee Cronbach.
Cronbach's can be shown to provide a lower bound for reliability under rather mild assumptions. [citation needed] Thus, the reliability of test scores in a population is always higher than the value of Cronbach's in that population. Thus, this method is empirically feasible and, as a result, it is very popular among researchers.
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Accuracy is also used as a statistical measure of how well a binary classification test correctly identifies or excludes a condition. That is, the accuracy is the proportion of correct predictions (both true positives and true negatives) among the total number of cases examined. [10]
Calcium chloride was apparently discovered in the 15th century but wasn't studied properly until the 18th century. [11] It was historically called "fixed sal ammoniac" (Latin: sal ammoniacum fixum [12]) because it was synthesized during the distillation of ammonium chloride with lime and was nonvolatile (while the former appeared to sublime); in more modern times (18th-19th cc.) it was called ...
The solubility in water depends on the type of salt. Sodium chloride can be dissolved in cold water to a concentration of 357 g∙l −1. Not only solubility differs between salts but also the conductivity. When performing a Bresle method test, not only sodium chloride is dissolved but also all other salts present on the surface.