Compute various measures of internal consistencies for tests or item-scales of questionnaires.
A list with two elements: the split-half reliability
and the Spearman-Brown corrected split-half reliability
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.
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