What is Spearman Brown reliability index?
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Also question is, what does the Spearman Brown formula do?
The Spearman–Brown prediction formula, also known as the Spearman–Brown prophecy formula, is a formula relating psychometric reliability to test length and used by psychometricians to predict the reliability of a test after changing the test length.
Furthermore, what is considered a good reliability coefficient? The closer each respondent's scores are on T1 and T2, the more reliable the test measure (and the higher the coefficient of stability will be). Between 0.9 and 0.8: good reliability. Between 0.8 and 0.7: acceptable reliability. Between 0.7 and 0.6: questionable reliability.
Keeping this in consideration, what is reliability index?
Item reliability is simply the product of the standard deviation of item scores and a correlational discrimination index (Item-Total Correlation Discrimination in the Item Analysis Report). So item reliability reflects how much the item is contributing to total score variance.
How do you determine reliability?
Correlate the test scores of the two administrations of the same test. – Parallel Forms Reliability: Determines how comparable are two different versions of the same measure. To calculate: Administer the two tests to the same participants within a short period of time. Correlate the test scores of the two tests.