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 Category	Process
Ratio	A 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.
Proportion	A 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).

Measure Specifications by Measure Category

	Ratio	Proportion	CV
Target/Initial Population	Required	Required	Required
Denominator	Required	Required	Required*
Denominator Exclusion	Optional	Optional	Optional*
Denominator Exception	Not Permitted	Optional	Not Permitted
Numerator	Required	Required	Not Permitted
Numerator Exclusion	Optional	Optional	Not Permitted

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

Last Updated: May 2025