Statistical power as a function of Cronbach alpha of instrument questionnaire items

Table 4 Statistical power of the between-group within-group test T _TS (32): σ _μ = 1

			k = 5		k = 10
N per group	Δ _TS	C _α	φ _TS	\({\tilde{\varphi}}_{\mathit{\mathsf{T}}\mathit{\mathsf{S}}}\)	φ _TS	\({\tilde{\varphi}}_{\mathit{\mathsf{T}}\mathit{\mathsf{S}}}\)
50	0.7	0.5	0.697	0.676	0.697	0.697
		0.6	0.774	0.758	0.774	0.760
		0.7	0.834	0.812	0.834	0.813
		0.8	0.879	0.872	0.879	0.882
		0.9	0.913	0.901	0.913	0.895
100	0.5	0.5	0.705	0.682	0.705	0.679
		0.6	0.782	0.791	0.782	0.769
		0.7	0.841	0.820	0.841	0.832
		0.8	0.885	0.879	0.885	0.908
		0.9	0.918	0.929	0.918	0.912

Note: N per group: number of subjects per group; k: number of items; \({\varDelta}_{\mathit{\mathsf{T}}\mathit{\mathsf{S}}}={\delta}_{\mathit{\mathsf{T}}\mathit{\mathsf{S}}}/{\sigma}_{\mu }\); C _α: Cronbach alpha; φ _TS: theoretical power (34); \({\tilde{\varphi}}_{\mathit{\mathsf{T}}\mathit{\mathsf{S}}}\): simulation-based empirical power

ISSN: 1471-2288