ECV_SG {BifactorIndicesCalculator}

ECV_SG

Description

Computes an ECV index for all factors which can be interpreted as the proportion of common variance of all items which is due to the specific factor; ECV_SG should be read 'ECV of a specific factor with respect to the general factor.' Here, ECV is computed with respect to the items of the general factor using the specific factor loadings in the numerator; Stucky and Edelen (2015, p. 199) refer to this index simply as 'specific-dimension ECV.' Note that ECV_SG of the general factor is simply the ECV. In the Excel version of the Bifactor Indices Calculator (Dueber, 2017), this form of ECV is referred to as 'ECV (S&E).' ECV_SG is called by bifactorIndices and the various convenience functions for exploratory models and/or Mplus output, which are the only functions in this package intended for casual users.

Usage

ECV_SG(Lambda)

Arguments

Lambda

is a matrix of factor loadings. Be sure that all factors have the same variance before calling this function.

Value

A vector of ECVs for all factors

References

Dueber, D. M. (2017). Bifactor Indices Calculator: A Microsoft Excel-based tool to calculate various indices relevant to bifactor CFA models. doi: 10.13023/edp.tool.01

Stucky, B. D., & Edelen, M. O. (2015). Using hierarchical IRT models to create unidimensional measures from multidimensional data. In S. P. Reise & D. A. Revicki (Eds.), Handbook of item response theory modeling: Applications to typical performance assessment (pp.183-206). New York: Routledge.

See Also

ECV_SS, ECV_GS, bifactorIndices

Examples

Lambda <- matrix(c(.82, .10,   0,   0,
                   .77, .35,   0,   0,
                   .79, .32,   0,   0,
                   .66, .39,   0,   0,
                   .51,   0, .71,   0,
                   .56,   0, .43,   0,
                   .68,   0, .13,   0,
                   .60,   0, .50,   0,
                   .83,   0,   0, .47,
                   .60,   0,   0, .27,
                   .78,   0,   0, .28,
                   .55,   0,   0, .75),
                   ncol = 4, byrow = TRUE)
colnames(Lambda) <- c("General", "SF1", "SF2", "SF3")
ECV_GS(Lambda)