Estimation by Analogy

Approach

• The effort of a job is estimated by comparing it to one ormore similar jobs.


• Collect or maintain project data: job attributes and actualoutcomes
  
  • May be as simple as a spreadsheet. If a database is used, canexplore it with queries.
  
  

Advantages: Accurate if project data available. Canbe applied at the task level.

Requirements: Depends on finding similar jobs.Must also assess the degree of similarity.

Recommended use: When you have or can gatherdata on similar jobs.

Procedure:

• Choose variables for characterizing projects.
  • Examples are application domain, development phasesincluded, libraries employed, number of dialogs, number ofdrawing elements, number of tables, and critical productcharacteristic (performance, ease of data entry, etc.)
• Gather data on completed projects and comparetheir variables.
• Judge the confidence that can be placed in theanalogies found.
  • Are there other important variables in these projects thataffected the outcomes?
• Estimate the effort for the new project.
  • Consider a weighted average, where weights are based onhow well each analogy project relates to the project beingestimated.