svycralpha {survey}

Cronbach's alpha

Description

Compute Cronbach's alpha coefficient of reliability from survey data. The formula is equation (2) of Cronbach (1951) only with design-based estimates of the variances.

Usage

svycralpha(formula, design, na.rm = FALSE)

Arguments

formula

One-sided formula giving the variables that make up the total score

design

survey design object

na.rm

TRUE to remove missing values

Value

A number

References

Cronbach LJ (1951). "Coefficient alpha and the internal structure of tests". Psychometrika. 16 (3): 297-334. doi:10.1007/bf02310555.

Examples

data(api)
dstrat<-svydesign(id = ~1, strata = ~stype, weights = ~pw, data = apistrat, 
    fpc = ~fpc)
svycralpha(~ell+mobility+avg.ed+emer+meals, dstrat)