Jak vypočítat Cronbach's Alpha
Co je Cronbach's Alpha?
Cronbach's alpha (α) measures internal consistency reliability — whether items measuring the same construct produce correlated scores. α > 0.7 is generally acceptable; > 0.9 is excellent.
Průvodce krok za krokem
- 1α = (k × r̄) / (1 + (k−1) × r̄)
- 2k = number of items · r̄ = average inter-item correlation
- 3Higher α: items are more redundant/internally consistent
Worked Examples
Vstup
10-item scale · avg inter-item r=0.4
Výsledek
α = 0.87 — good reliability
(10×0.4)/(1+9×0.4)=0.87
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