Spearman–Brown prophecy formula

E622307
measurement theory concept psychometric formula statistical formula

The Spearman–Brown prophecy formula is a psychometric equation used to predict how changes in test length will affect the reliability of a measurement instrument.

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All labels observed (1)

Label Occurrences
Spearman–Brown prophecy formula canonical 2

Statements (47)

Predicate Object
instanceOf measurement theory concept ⓘ
psychometric formula ⓘ
statistical formula ⓘ
appliesTo parallel tests ⓘ
assumes error scores are uncorrelated ⓘ
items are parallel ⓘ
true score model of classical test theory ⓘ
category classical test theory formula ⓘ
psychometric reliability estimation method ⓘ
field classical test theory ⓘ
educational measurement ⓘ
psychometrics ⓘ
hasFormula ρ_new = (k · ρ_old) / (1 + (k − 1) · ρ_old) ⓘ
limitation assumes added items are of same quality as original items ⓘ
can overestimate reliability if new items are weaker ⓘ
requires estimate of original reliability ⓘ
namedAfter Charles Spearman NERFINISHED ⓘ
William Brown NERFINISHED ⓘ
relatedTo Cronbach's alpha NERFINISHED ⓘ
internal consistency ⓘ
parallel forms reliability ⓘ
split-half reliability coefficient ⓘ
relatesConcept number of items ⓘ
split-half reliability ⓘ
test length ⓘ
test reliability ⓘ
specialCaseOf reliability generalization for parallel tests ⓘ
typicalInput observed reliability of a test ⓘ
planned change in number of items ⓘ
typicalOutput predicted reliability of modified test ⓘ
usedFor assessing impact of item duplication on reliability ⓘ
estimating reliability of a longer test ⓘ
estimating reliability of a shorter test ⓘ
predicting reliability after changing test length ⓘ
test length planning ⓘ
usedIn ability testing ⓘ
aptitude testing ⓘ
educational testing ⓘ
personality measurement ⓘ
psychological assessment ⓘ
questionnaire design ⓘ
scale development ⓘ
survey research ⓘ
test construction ⓘ
variable k (factor of test length change) ⓘ
ρ_new (predicted reliability) ⓘ
ρ_old (original reliability) ⓘ

Referenced by (2)

Full triples — surface form annotated when it differs from this entity's canonical label.

Charles Spearman → knownFor → Spearman–Brown prophecy formula ⓘ
Charles Spearman → developedMethod → Spearman–Brown prophecy formula ⓘ