multicon (version 1.6)

alpha.aci: Alpha Confidence Interval

Description

Computes the asymptotic confidence interval for Cronbach's alpha following the method outlined by Koning & Franses (2003).

Usage

alpha.aci(x, k, n, CI = 0.95)

Arguments

x

An alpha coefficient to compute a confidence interval around.

k

The number of items on which alpha was computed.

n

The number of sampling units (observations) on which alpha was computed.

CI

A numeric element between .00 and 1.00 indicating the desired confidence level.

Value

Lower Limit

Lower limit of confidence interval

Upper Limit

Upperlimit of confidence interval

Details

Koning & Franses (2003) describe several methods for computing confidence intervals around Cronbach's alpha coefficient. This function returns what Koning and Franses (2003) refer to as the asymptotic confidence interval for alpha. The confidence interval is asymptomic and not necessarily symmetrical. For more info, see Koning and Franses (2003).

References

Koning, A. J. & Franses, P. H. (2003). Confidence Intervals for Cronbach's Alpha Coefficient values. ERIM Report Series Reference No. ERS-2003-041-MKT. Available at SSRN: http//ssrn.com/abstract=423658

See Also

alpha.xci vector.alpha

Examples

	#Compute the asymptotic CI for an observed Cronbach's alpha 
	#of .7 on 200 observaitons from a 10 item scale'
alpha.aci(.7,10,200)