Introduction

The Regression Activity allows you to view correlations on a Site, view the CuSUM and set targets based on the CuSUM and Regression. This activity is not available from the main Activity Menu; it is only available via right click of a Site or through the Site Overview activity.

Navigation

Click on the Site in the Site Overview Activity

Click Actions in the top right of the screen to allow you to navigate to other activities within Sigma including Regression

Click on Regression

Alternatively, right-click on a Site and select Regression  from the menu

Regression Correlations

Automatic Regressions

Sigma will automatically check the system to find any correlations with an R² value of 0.9 or greater. The R² value is called the coefficient of determination and is a statistical measure of how close the data points are to the regression line. Typically, a value of 0.9 or above represents a good correlation and indicates that the two datasets are related, i.e. a 90% correlation between the variation in consumption and the influencing dataset.

Correlations will be between two data sets and those found automatically will display as follows:

Manual Regressions

Correlations can also be setup manually by selecting  and choosing the required correlation items within the setup screen.

To view the regression correlation, right-click the image and select  or double-click the regression image

You will now see three tabs - Regression, CUSUM and Control Chart

Regression

Graph

• The graph plots the Dependent Data against the Independent Data and draws a line of best fit

Overview

• The Overview chart shows the dependent data and independent data for the regression period and part of the historic period too
• Dragging your mouse over this chart will update the regression period displayed
• The Overview Graph can be minimised by clicking the Overview header bar

Details

This section shows gradient and intercept of the graph.

The gradient and intercept can be adjusted by selecting  and entering a value in the popup box

To remove the gradient and intercept click  

When a custom gradient is set the R² values are not available.

The details section displays both the Correlation Coefficient and Coefficient of Determination.

Regression Period

Use the start date to choose the start period for the graph, either selecting the drop down boxes or the calendar icon .

Set the end date for the graph in the same way.

Manage Regression Targets

• If a regression is found, it is automatically saved as Original Correlation, this correlation cannot be amended
• A New performance line is also created which can be amended and saved as a new regression target

Table tab

The screen defaults to show the data in a graph. This can be changed to show as a table.

Click on  to display the data points that are plotted on the graph

Uncheck any line item that you want to exclude from the graph 

Excluding points from the graph will recalculate the line of best fit

The date displayed within the table is the end date for that period

The table and charts can be saved by clicking 

CuSUM

Click on 

Graph

The graph shows the cumulative data based on the CUSUM period.

Clicking and dragging your mouse over the graph will zoom into the data.

Overview

The Overview chart (bottom of the screen) shows the dependent data and independent data for the CUSUM period and part of the historic period too

Dragging your mouse over this chart will update the CUSUM period displayed

If the CUSUM period is different to the Regression period then you will see two colours highlighted on the overview. Blue is the regression period and purple the CUSUM period

The Overview Graph can be minimised by clicking the Overview header bar

Details

CuSUM and CuSUM CO₂ will always be 0.00 when moving straight from Regression without changing the CuSUM period.

When the CuSUM period is changed then anything above the 0 value based on the regression period will be calculated and listed in both kWh's and CO₂ emissions.

Data Analysis

Tick the Show V-Mask box to add a V-Mask target onto the CuSUM. To confirm target creation select  in the resulting popup window

By default a truncated V-Mask will be applied, adding a green layer to the graph

There are 3 types of V-Mask targets available as follows:

Full mask

Snub-nosed mask

Truncated mask

Tick Show Fixed Targets to add a CuSUM fixed target. To confirm target creation select  in the resulting popup window.

CuSUM Period

Use the start date to choose the start period for the graph, either selecting the drop down boxes or the calendar icon  

Set the end date for the graph in the same way

Targets

This section displays any targets that have been created on the CuSUM

To change any of the settings, right-click on the target and select Edit

To remove a target, right-click on the target and select Remove

If you edit a V-Mask Target you will be presented with the following window

If you edit a CuSUM target you will be presented with the following window

Update the settings as required and click OK

The Targets will only create an event if the first point of data is outside the tolerance range by >5% or if there are two consecutive points of day outside the tolerance range but with the 5% range.

Table

Selecting the  tab to show the data points that are plotted on the graph

The date displayed within the table is the end date for that period

The table and charts can be saved by click 

Control Chart

It is not possible to go directly from Regression to the Control Chart as it is a designed as a stepped approach. 

Navigate from Regression to the Control Chart via CuSUM by clicking  then 

Graph

The graph will display data for the same period that has been set in the CuSUM

The graph displays 

Control Lines - accepted areas of data based on the control limit

Exceptions - areas which fall outside of the control limit

Difference line - data for the period being presented

Overview

The Overview Graph highlights the current target period by default and displays historic and future data

The Overview Graph can be minimised by clicking the Overview header bar

Targets

By default a New Control Target will be created for the user to amend as required. This target is not saved unless you click the Save button

The Targets section details the current control line parameters as well as allowing you to add and remove targets. 

Control Lines

To amend the control lines applied change the control limit

Alternatively you can manually drag the control lines on the graph, to do this select  and click and drag on the graph to set desired control limits

To remove the Control Limits from the graph uncheck .

The Targets will only create an event if the first point of data is outside the tolerance range by >5% or if there are two consecutive points of day outside the tolerance range but with the 5% range.