Working with extrapolation models

An extrapolation model estimates metric values as functions of other metrics. It forecasts for metric values in relation with other metrics based on the correlation defined in the correlation analysis. 

For example, based on a correlation between a server CPU load and a given business driver, data can be extrapolated to determine whether the existing server will be able to sustain a 30% increase of business drivers, and what the average CPU load would be in this condition.

Extrapolation models are of the following types:

• Extrapolate performance versus load analysis: Correlates performance metrics, such as CPU utilization or response time, with load metrics, such as total events.
• Extrapolate duration versus load analysis: Correlates a business driver with itself over time (for example, batch elapsed time versus a business driver).
• Extrapolate load versus load analysis: Correlates a for-instance business driver with a technical business driver, such as daily peak versus total daily business driver.
• Extrapolate performance versus performance analysis: Correlates system resource metrics.

Example of an extrapolation model for a performance versus load analysis

The region in red represents where the set threshold is exceeded. The number of visits can be increased (to the right end of the red arrow) without exhausting the chosen threshold.

To create an extrapolation model

The following video (4:04) illustrates the process of creating an extrapolation model.

 https://youtu.be/f1mnqbboeY8

1. In Workspace, click Domains, Services & Applications > domainName  > Works folder.
2. Click Add and select Add model. The model creation wizard is displayed. 

3. On the Model type page, select Extrapolate correlation between metrics (EXTRAPOLATION MODEL) and click Next.

4. On the Correlation analysis page, select the analysis that you want to base your extrapolation on from the list, and click Next.

5. On the Name page, type a Name and Description for the model, and click Next.
   
   A default name based on the selected analysis is displayed. You can change it as required. You can also click  to select the parameters you want to include in the model name.

6. On the Summary page, click Finish.
   The Extrapolation Model's detail page is displayed, listing the analysis that the model is based on. The details page displays the following: 

• • A link to the analysis that the model is extrapolated from. Clicking on the link takes you to that analysis page.
  • Prediction scenarios table that lists all available scenarios and allows you to add new ones.