alpha_cronbach: Cronbach's alpha

In SICSresearch/LatentREGpp: Item Response Theory Implemented in R and Cpp

Description

Cronbach's alpha measures how correlated are the items in a test. Taken from ltm::cronbach.alpha

Usage

alpha_cronbach(data,standardized,CI,probs,B,na.rm)

Arguments

data	a matrix or a Dataframe that holds the test response data
standardized	Standarize data
CI	boolean
probs	Vector of probabilities
B	Vector Size
na.rm	Remove Na values

Details

the coefficient is calculated

α = (n/n-1)*(1 - (∑ V_i/V_t))

where

V_t

is the variance of test scores and

V_i

is the variance of item scores. It is desirable that the items are closely interrelated (coefficient near 1). This function was extracted from multilevel_2.5 package.

Value

Cronbach's alpha for the test and the number of individuals of test.

References

Cronbach L. J. (1951) Coefficient Alpha and the internal structure of tests. Psychometrika, 16,297-334

SICSresearch/LatentREGpp documentation built on May 9, 2019, 11:13 a.m.