Table 3 A priori power estimated with the Raschpower procedure from a pilot study and impact of misspecified parameters on the power ( \(1-\hat {\beta }\) )
Estimations used to determine the power with Raschpower | Estimated power | Misspecified parameters | |||
|---|---|---|---|---|---|
Item parameters | Group effect | Variance of the latent variable | \({1-\hat {\beta }}\) | Item parameters | Variance |
Pilot: \(\hat {\delta }_{\textit {jpPILOT}}\) | \(\hat {\gamma }_{\textit {PILOT}}=0.1888\) | Pilot: \(\hat {\sigma }_{\textit {PILOT}}^{2}=0.7858\) | 0.3837 (a priori) | ||
ELCCA: \(\hat {\delta }_{\textit {jpELCCA}}\) | \(\hat {\gamma }_{\textit {PILOT}}=0.1888\) | Pilot: \(\hat {\sigma }_{\textit {PILOT}}^{2}=0.7858\) | 0.3771 | YES | |
Pilot: \(\hat {\delta }_{\textit {jpPILOT}}\) | \(\hat {\gamma }_{\textit {PILOT}}=0.1888\) | ELCCA: \(\hat {\sigma }_{\textit {ELCCA}}^{2}=1.0864\) | 0.3004 | YES | |
ELCCA: \(\hat {\delta }_{\textit {jpELCCA}}\) | \(\hat {\gamma }_{\textit {PILOT}}=0.1888\) | ELCCA: \(\hat {\sigma }_{\textit {ELCCA}}^{2}=1.0864\) | 0.2983 | YES | YES |