# Correlation map

## Overview

A correlation map shows the association between business driver metrics or performance metrics inspected in a single analysis.

The association between different business driver metrics (performance metrics) is used to evaluate the correlation between the metrics. This correlation helps with understanding the dynamics of the application.

For example, if a new metric, number of downloads per hour, becomes available in BMC TrueSight Capacity Optimization, you might want to determine whether a correlation exists between this metric and the page requests per hour metric that was analyzed in Business driver map. This is a load versus load analysis (LLA), as shown in the following table:

Metric

Page Requests

Rows represent the Y axis in correlation charts, and columns the X axis. Each X-Y couple on the map generates a scatter chart that displays a point (dot) for each time interval for which the counters on X and Y are defined. In this case, two metrics of the same type (business driver or performance) are plotted in scatter charts. A cloud of points around a line (as seen in performance versus load analysis) is the linear regression. The denser the point scattering around the line, the lower the correlation. The line has an angular coefficient (the slope) and an intercept.

## Slope

Slope is the ratio between a Y-axis metric and an associated X-axis metric.

Although similar in purpose to the service demand in business driver maps, this parameter is calculated as the ratio of the first business driver metric (or performance metric) to the second.

For example, you may obtain the following value:

Metric

Page Requests

0.01±10%

This value can be used for further analyses, for example, to identify business driver mixes and cause-effect relationships.

## Intercept

Intercept is the Y-axis offset that exists even when the X-axis metric is zero.

Note

Indicating two X values (X1,X2) on the map means that Y needs to be analyzed against two independent variables, X1 and X2. This can lead to two distinct univariate analyses – Y against X1 and Y against X2, or to a single multivariate analysis. BMC TrueSight Capacity Optimization supports both these analyses.

## Correlation-map-based analysis

The following types of analysis are based on an associated correlation map:

A load versus load analysis (LLA) shows the relation between two business driver metrics to analyze their potential correlation. Its main objective is to identify the impact of peaks driven by one business driver on another, and to correlate them.

The following figures show examples of how two load versus load analysis scatter charts appear in BMC TrueSight Capacity Optimization:

A load versus load analysis scatter chart showing visits versus page views

### Performance versus performance analysis

In performance versus performance analysis, two performance metrics, such as peak performance and average peak performance, are analyzed together to find potential correlations between them.

The following figure shows an example of a performance versus performance analysis of two standard database metrics:

Performance versus performance analysis of two standard database metrics

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