Content Validity Indices for Instrument Development // Computes content validity indices commonly used in instrument development and questionnaire validation, including the Item- level Content Validity Index (I-CVI), Scale-level Content Validity Index (S-CVI), modified kappa adjusted for chance agreement, Aiken's V, and Lawshe's Content Validity Ratio (CVR). Methods follow Lynn (1986) doi:10.1097/00006199-198611000-00017, Polit and Beck (2006) doi:10.1002/nur.20147, Aiken (1985) doi:10.1177/0013164485451012, and Lawshe (1975) doi:10.1111/j.1744-6570.1975.tb01393.x.