Confidence intervals around alpha do not resolve the problem because they inherit alpha's failure to indicate knowledge-test reliability¶

Claim · All claims
Evidence · 1 study · theoretical r3 · q2
Currency · newest study 2025 · not yet checked against its sources · not reviewed by a person

Subclaims¶

q2 i? Reporting confidence intervals for alpha is recommendable, but if alpha does not indicate reliability for heterogeneous constructs, its confidence interval does not either. → Peter A. Edelsbrunner 2025

Evidence¶

Peter A. Edelsbrunner 2025¶

Peter A. Edelsbrunner, Bianca A. Simonsmeier, Michael Schneider. (2025). The Reliability, But Not the Cronbach's Alpha, of Knowledge Tests Matters: Response to Zitzmann and Orona (2025). Educational Psychology Review. https://doi.org/10.1007/s10648-025-10023-5

q2 · i? · theoretical · r3

Theoretical argument responding to ZaO's recommendation of cutoff values for the confidence interval around alpha: the authors agree confidence intervals are generally useful and should be reported, but argue they do not help evaluate knowledge-test reliability.

"However, if alpha does not indicate test reliability for general conceptual reasons, then its confidence interval also does not indicate the reliability."

Discussion¶

Related Claims¶

• Cronbach's alpha does not generally indicate the reliability of knowledge tests because knowledge is a heterogeneous construct — a broader claim this one bears on
• Retest reliability may be more appropriate than alpha for knowledge tests, but requires a testing interval without learning — related
• Meta-analytic average Cronbach's Alpha of domain-specific knowledge tests is 0.85 with expected item intercorrelation of 0.22 — related
• A low alpha does not necessarily indicate high content validity, because reliability and validity can both be high — related
• Fixed alpha cutoff values create publication bias so knowledge tests with low alphas are underrepresented in the literature — related