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  The derivation of a ratio’s score is 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). The key to the definition of a ratio is that the numerator and the denominator represent the count of different kinds of people, things, 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 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
The table defines the components relevant for the three measure categories.

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 use measure population instead of denominator and measure population exclusion instead of denominator exclusion.
Last Updated: Oct 2022