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

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: Dec 2022