How do you interpret Spearman-Brown?

The Spearman-Brown formula is used to predict the reliability of a test after changing the length of the test….Example: How to Use the Spearman-Brown Formula

  1. Predicted reliability = kr / (1 + (k-1)r)
  2. Predicted reliability = 2*. 74 / (1 + (2-1)*.
  3. Predicted reliability = 0.85.

What does the Spearman-Brown correction 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.

Why is Spearman-Brown formula for split-half method?

The reasoning is that if both halves of the test measure the same construct at a similar level of precision and difficulty, then scores on one half should correlate highly with scores on the other half.

How do you read a split-half reliability?

The higher the correlation between the two halves, the higher the internal consistency of the test or survey. Ideally you would like the correlation between the halves to be high because this indicates that all parts of the test are contributing equally to what is being measured.

How is Spearman-Brown prophecy calculated?

In the formula(4) r Spearman -Brown = n r 1 + ( n − 1 ) r n is the factor by which the number of items will be multiplied, and r is the reliability (internal consistency) of the questionnaire.

How does test length affect reliability?

(i) Length of the Test: Reliability has a definite relation with the length of the test. The more the number of items the test contains, the greater will be its reliability and vice-versa. Logically, the more sample of items we take of a given area of knowledge, skill and the like, the more reliable the test will be.

For which kind of reliability is the Spearman-Brown formula relevant quizlet?

The Spearman-Brown prophecy formula, is a formula relating psychometric reliability to test length.

What causes low test level reliability?

The difficulty level and clarity of expression of a test item also affect the reliability of test scores. If the test items are too easy or too difficult for the group members it will tend to produce scores of low reliability. Because both the tests have a restricted spread of scores.

How do you determine reliability of a test?

Calculating reliability in Teacher-made Tests variance of the total test, subtract it from 1, and multiply that result by 2. The result is the split half reliability of your quiz. Good tests have reliability coefficients of .

How do you know if a test is reliable?

Reliability refers to how dependably or consistently a test measures a characteristic. If a person takes the test again, will he or she get a similar test score, or a much different score? A test that yields similar scores for a person who repeats the test is said to measure a characteristic reliably.

Why do longer tests have higher reliability?

D. Some believe that longer multiple choice tests tend to be more reliable because more items automatically reduce the error of measurement.

Why is it called the Brown-Spearman formula?

This formula should be referred to as the Brown-Spearman formula for the following reasons: First, the formula we use today is not Spearman’s (1910) version, but Brown’s (1910). Brown (1910) explicitly presented this formula as a split-half reliability coefficient, but Spearman (1910) did not.

When to use a Spearman correlation analysis?

A Spearman correlation analysis can therefore be used in many cases in which the assumptions of the Pearson correlation (continuous-level variables, linearity, heteroscedasticity, and normality) are not met.

When was the Spearman-Brown Method published?

The method was published independently by Spearman (1910) and Brown (1910). The Spearman-Brown Formula, also known as the Spearman-Brown Prophecy Formula or Correction, is a method used in evaluating test reliability.

Is Spearman-Brown coefficient of reliability still relevant?

Although the Spearman-Brown formula is rarely used as a split-half reliability coefficient after the development of tau-equivalent reliability, this method is still useful for two-item scales.