Split-Half Reliability — item_split

Compute various measures of internal consistencies for tests or item-scales of questionnaires.

Usage

item_split_half(x, digits = 3)

Arguments

x: A matrix or a data frame.
digits: Amount of digits for returned values.

Value

A list with two elements: the split-half reliability splithalf and the Spearman-Brown corrected split-half reliability spearmanbrown.

Details

This function calculates the split-half reliability for items in x, including the Spearman-Brown adjustment. Splitting is done by selecting odd versus even columns in x. A value closer to 1 indicates greater internal consistency.

References

Spearman C. 1910. Correlation calculated from faulty data. British Journal of Psychology (3): 271-295. doi:10.1111/j.2044-8295.1910.tb00206.x
Brown W. 1910. Some experimental results in the correlation of mental abilities. British Journal of Psychology (3): 296-322. doi:10.1111/j.2044-8295.1910.tb00207.x

Examples

data(mtcars)
x <- mtcars[, c("cyl", "gear", "carb", "hp")]
item_split_half(x)
#> $splithalf
#> [1] 0.9070215
#> 
#> $spearmanbrown
#> [1] 0.9512441
#>