statistic for testing content validity: the degree to which items in an instrument reflect the content universe to which the instrument will be generalized
C. H. Lawshe. A Quantitative Approach to Content Validity. Personnel Psychology, 28(4):563–575, December 1975. doi:10.1111/j.1744-6570.1975.tb01393.x.
@article{lawshe_quantitative_1975,
author = {Lawshe, C. H.},
doi = {10.1111/j.1744-6570.1975.tb01393.x},
issn = {1744-6570},
journal = {Personnel Psychology},
language = {en},
month = {December},
number = {4},
pages = {563-575},
title = {A {{Quantitative Approach}} to {{Content Validity}}},
volume = {28},
year = {1975}
}