Guideline: Measures, Metrics and Attributes
This guideline provides definitions used throughout the Performance Measurement System material. Examples from the identified set of metrics associated with this material are used in conjunction with definitions to clarify the text for the definitions.
Relationships
Main Description

The terms of measure and metric have had multiple uses over the years. In some cases they are even used synonymously. While they are not synonymous they do relate to common information. The definitions used in the Performance Measurement System are base on the reference, McGarry, John, David Card, Cheryl Jones, Beth Layman, Elisabeth Clark, Joseph Dean, and Fred Hall, Practical Software Measurement,. Boston; Addison Wesley 2002.

  • Indicator: an interpretation of measures and may include subjective data
  • Measure: a generalized term referring to base and derived measures
  • Derived measure: typically referred to as a metric and obtained by some calculation
  • Base measure: a single attribute valued with some representing the attribute
  • Attribute: a unit of measure (defect, hour, dollars, and so forth)

The following examples provide context for using the above definitions.

Example 1

Cost Variance Percentage measures project cost performance compared to project cost estimates. It is frequently used to evaluate cost management performance for both individual projects and project portfolios. This measure is composed of one attribute, two base measures, and a derived measure. Below is the algorithm for determining Cost Variance (CV) percentage.

CV = (Budget at Completion - Actual Cost) / Budget at Completion or simply,

CV = (BAC – AC) / BAC

Attribute
An attribute is not the value itself but what low level element will be used in determining the actual value. The attribute used for this measure is dollars.

Base Measure
The base measures are:
  • Budget at Completion (BAC) is the value of counting all of the dollars representing the budget to complete the effort at the time of the collection. A base measure for BAC might be $1.5 million.
  • Actual Cost (AC) is the value determined at the time of counting the dollars representing the all of the costs at the time of collection. A base measure for AC might be $0.50. The base measure represents what ever the value is at the time of collection as obtained by some method.

Derived Measure
The derived measure in this example is represented by CV, the percentage of the cost variance as determined by the calculation:

CV = (BAC - AC) / BAC

Indicator
Collecting all of the individual project base measures could provide an indicator for a portfolio of projects.

Portfolio Cost Variance = (Sum(BAC) - Sum(AC)) / Sum(BAC)

Example 2

Iteration velocity is used for measuring team capability. Velocity is a count of the number of units of work completed within a specified time period. A unit of work can be anything: function points, use case scenarios, test cases, etc. A specified period of time can be: weeks, months, iterations, and so forth.

Attribute
The attribute for velocity is unit of work.

Base Measure
The base measure is the count for a unit of work.

Derived Measure
The derived measure is the count for a unit of work within a specified time period.

Indicator
The indicator for velocity would be the interpretation of the team’s capability based on the evaluation of the results of the derived measure.