Gaming is when measured entities exploit weaknesses in the measurement system to tweak the data making their performance look better than it actually is. Includes limiting access to certain populations, neglecting care, or overuse of medications or services to ensure that the measure results are favorable.
Grey literature is unpublished or not commercially indexed material that can include any documentary materials issued by government, academia, business, and industry such as technical reports, working papers, and conference proceedings. For example, contributors to the New York Academy of Medicine Grey Literature website include the Agency for Healthcare Research and Quality (AHRQ), Centers for Disease Control and Prevention, the Department of Health and Human Services (HHS), The Joint Commission, National Academy of Sciences, RAND, and RTI International.
Gwet's AC1 is a quantitative measure of agreement of binary ratings between two raters (inter-rater reliability).