Specifications by Measure Category

Almost all technical specifications depend, at least in part, on the category of the specified measure. A calculation algorithm provides a score and derivation of the score determines the measure’s category. 

Determining Measure Categories

Measure CategoryProcess
RatioA ratio’s score is derived by dividing a count of one type of data by a count of another type of data (e.g., number of patients with central lines who develop infection divided by the number of central line days). In a ratio, the numerator and the denominator represent counts of different kinds of people, entities, events, or objects.
ProportionA proportion is a score derived by dividing the number of cases that meet a criterion for quality (the numerator) by the number of eligible cases within a given time frame (the denominator) where the numerator cases are a subset of the denominator cases (e.g., percentage of eligible women with a mammogram performed in the last year).
Continuous Variable
(CV)
A CV is a score in which the individual value for the measure can occur along a continuous scale and values can be aggregated using a variety of methods such as the calculation of a mean or median (e.g., mean number of minutes between the time when a patient presents with chest pain and the time of thrombolytic medications administration).
Categorical ValueA categorical value combines individual observations into distinct groups or categories without inherent numerical meaning or order. These values can be binary (e.g., yes/no) or qualitative (e.g., race, language, insurance type).
CountA count represents the raw number of occurrences of an event or entity within a specified time frame or population. There is no denominator as it is a tally of all cases/events that meet a defined criterion (e.g., the number of emergency department visits in one month).
Composite scaleA composite scale is a method used to combine multiple related items (e.g., questions) from a tool or instrument into a single summary score (e.g., a pain scale that averages scores from multiple questions on a survey about pain severity and duration).

Measure Specifications by Measure Category

Measure specifications may include different components based on the measure category. For example, numerators are used in ratio and proportion measures because they involve specific, countable units. However, they are not suitable for CV measures because data can take on any value within a range and are not limited to discrete units.

 RatioProportionCV
Target/Initial PopulationRequiredRequiredRequired
DenominatorRequiredRequiredRequired*
Denominator ExclusionOptionalOptionalOptional*
Denominator ExceptionNot PermittedOptionalNot Permitted
NumeratorRequiredRequiredNot Permitted
Numerator ExclusionOptionalOptionalNot Permitted

*CV measures may use measure population instead of denominator and measure population exclusion instead of denominator exclusion.

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