Lambda4 (version 3.0)

angoff: Compute Angoff Coefficient

Description

Angoff's coefficient is most appropriately used for estimating reliability in tests that can be split into two parts with unequal lengths. The calculation corrects for the inequality of length in the splits. Angoff's coefficient is also believed to handle congeneric test structures relatively well.

Usage

angoff(x, split.method = "even.odd", missing = "complete", standardize = FALSE)

Arguments

x

Can be either a data matrix or a covariance matrix

split.method

Specify method for splitting items?

missing

How to handle missing values.

standardize

When TRUE Results are standardized by using the correlation matrix instead of the covariance matrix for computation.

Value

angoff

The estimate of reliability.

Split

The split half key used to calculate angoff's coefficient.

References

Feldt, L. S., & Charter, R. A. (2003). Estimating the reliability of a test split into two parts of equal or unequal length. Psychological Methods, 8(1), 102-109.

Sedere, M. U. And Feldt, L. S. (1977), The Sampling Distributions Of The Kristof Reliability Coefficient, The Feldt Coefficient, And Guttman's Lambda-2. Journal Of Educational Measurement, 14: 53-62.

Feldt, L. S. (1975). Estimation of the reliability of a test divided into two parts of unequal length. Psychometrika, 40, 557-561.

Angoff, W. H. (1953). Test reliability and effective test length. Psychometrika, 18, 1-14.

Examples

angoff(Rosenberg, split.method="even.odd", missing="complete", standardize=FALSE)