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Glossary of Terms

90th percentile

This refers to the national 90th percentile, based upon national benchmarks computed by that National Committee for Quality Assurance (NCQA).  This reflects the top 10 percent of best performance across the nation. The goal of the Washington Health Alliance is to meet or exceed the NCQA national 90th percentile for care provided in our state.

Not all measures in the Community Checkup have this benchmark. The top 10 percent of performance is a relative number. If overall performance is low, the 90th percentile could mean that even at that level many patients are still not getting the care that they should. 

Accountable Community of Health 

Accountable Communities of Health (ACHs) bring together leaders from multiple health sectors around the state with a common interest in improving health and health equity. As ACHs better align resources and activities they improve whole person health and wellness.

There are nine ACHs that cover the entire state, with the boundaries of each aligned with the state’s Medicaid Regional Service Areas.

Area Deprivation Index (ADI)

ADI, which uses measures first created by Health Resources & Services Administration and was further refined by a research team at University of Wisconsin, allows for ranking across 10 deciles of advantage that factor in 17 census measures on education, income, employment, and housing quality. However, ADI does not factor in language, race, or ethnicity when determining advantage; nor does it include any aspect of risk related to health or health status. With ADI, socioeconomic advantage experienced by people living in Washington State neighborhoods is ranked 1 through 10 with 1 being the most advantaged neighborhoods (census blocks) based on the 17 census measures, and 10 being the least advantaged. In displaying ADI with quality measures, the Washington Health Alliance reports decile 0, which means there was no ADI information available for that corresponding quality measure data.

Confidence interval

The range of values calculated by a formula that determines the degree of confidence that the true value is contained within the range (typically 95 percent). In other words, a range of values that describes the uncertainty surrounding an estimate. The span of the confidence interval will be wider when the denominator is smaller and narrower when the denominator is larger.


The total population that was eligible for a measure. The denominator typically represents actual people.  For example, for a diabetes measure, the denominator is the number of patients who met the criteria for having diabetes (as stated in the measure specifications).  In the access to care measures, the denominator is the total number of enrollees who live in a selected area, for example a county. However, the denominator can reflect other things such as total hospital stays or total prescriptions.  For example, in the generic prescribing measures the denominator is the total prescriptions of a certain type of medication.

Measure steward

The organization that is responsible for maintaining and providing the methodology for a particular measure, including the specifications (or detailed definitions).


The number of elements (e.g. patients, visits, prescriptions) from the denominator that are considered compliant (or non-compliant in cases where lower rates are better) for the measure. For example, in the Blood sugar (HbA1c) testing for people with diabetes measure, the numerator is the total number of people who received a blood sugar (HbA1c) test among those who met the criteria for having diabetes (denominator).

State average

The overall rate for a measure across Washington state.