Calibration Tab

Calibration factors are used to support the error correction part of the modeling process. Across-day error correction is activated for a model by checking the Calibrate box on the Model Tab of the Model Properties dialog. Within day error correction is activated by checking the Tune box on the Model Tab. The Model Calibration tab provides data relevant to the across-day error correction process.

Calibration factors are calculated from model performance statistics over recent historical days. These factors are calculated by selecting the Calibration Backcast option on the Actions menu or by pressing the corresponding Toolbar button. In automated systems, this action will be scheduled to be executed before or as part of a forecast generation process.

Backcast Calculation

The Calibration Backcast action causes the model to be executed for a set of recent days. The number of days is determined by the Back Calibration settings, Calibration Weight Set on the Model Tab. If the Calibration Weight Set goes back seven days, then a seven day backcast will be executed. The number of days can be further limited by setting the Calibrate>Threshold Days setting to a smaller value.

The backcast logic implements a string of backcasts. For each backcast day, the actual weather data is used, but the load data for the backcast day is hidden from the model. If the model has dynamic components (like one-hour lag values), the prior hour data are hidden during the forecast day. The model predicted values from this process are stored and residuals are computed for the backcast period. These residuals are used to compute the Calibration Factors.

Display

The Calibration Tab displays the calibration information for the model selected in the Model Selection box on the Toolbar. The Calibration Tab has two modes, Backcast Period Mode and Forecast Factors Mode. The mode is selected using the Mode Selection box on the Toolbar.

  • Backcast Period Mode. On the second dropdown on the Toolbar, select Backcast to enter this mode. This will show the model Backcast Ratios (Actual/Predicted) for the historical backcast days. The chart shows the Actual, Predicted, and Residual values for the backcast days. The grid shows computed Backcast Ratios (Actual/Predicted) for each backcast day and interval.
  • Forecast Factors Mode. On the second dropdown on the Toolbar, select Factors to enter this mode. This will show the forecast multiplier factors for each of the forecast days. These multipliers are computed from the historical Backcast Ratios and the Back Calibration Weights. The multipliers allow the user to weight some backcast days more heavily than others. For example, when forecasting values for a Monday, we could place heavy weight on the prior two weekdays (Thursday and Friday), which are 3 and 4 days back from Monday. In contrast, when forecasting values for a Wednesday, we could place heavy weight on the prior two days (Monday and Tuesday), which are 1 and 2 days back from Wednesday.

In both cases, a graph of the data is shown at the top of the workspace and multipliers are shown at the bottom of the workspace. The data are read only.

Backcast Period Mode

The Backcast Period Mode shows the backcast calculation results. The chart at the top shows the actual data values for the backcast period, the backcast predicted values and the corresponding residuals. Chart components are:

  • Title. This appears in the upper left-hand corner of the chart gives the date range for the backcast period. If the chart is too compressed, this element will not be shown. Stretch the chart area (make it taller) to make this visible.
  • Check Box Legend. This appears in the upper right-hand corner of the chart and includes a check box for each of the three series. Uncheck a series to remove it from the chart. If the chart is too compressed, this element will not be shown. Stretch the chart (make it taller) to make this visible.
  • Scroll Ribbon. This appears below the chart. The ribbon shows the full range of available values and provides a range selector that represents the selected range and that can be used to shift the range left or right or to make the range broader or narrower.

The grid shows the Backcast Ratios, which are computed as Actual/Predicted. For example, if the predicted value is 1000 and the actual value is 1015, the value shown in the grid will be 1.015. Cells in the grid are color coded.

  • When the model is too low (running cold), the cells are shaded light blue or deep blue. Backcast ratios in this case will be greater than 1.0, indicating that we need to scale the forecasts up.
  • When the model is too high (running hot), the cells are shaded light red or deep red. Backcast ratios in this case will be less than 1.0, indicating that we need to scale the forecasts down.

Forecast Factors Mode

The Forecast Factors Mode show the forecast multiplier factors for each of the forecast days. These multipliers are computed from the historical Backcast Ratios and the Back Calibration Weights. The Weights are defined by day of the week and length of lag, allowing the user to weight the Backcast Ratios differently for different days of the week.

In Forecast Factors Mode, the chart has two versions controlled by the Contributors Mode. To toggle between these two versions, go to the View menu and click on the Contributors Mode option or press the corresponding Toolbar button.

  • Contributors Mode Off. In this mode, the chart shows the Calibration Factors for all days in the forecast period. The chart is one day wide, and each line on the chart shows the Factors for a specific forecast day.
  • Contributors Mode On. In this mode, the chart shows the Calibration Factors for a single day. It also shows the lagged days that contribute to the calculation of the Calibration Factors. These days are in two groups. Actual Contributors are historical days for which Backcast Factors are computed directly based on actual load data for those days. Forecast Contributors are days where Backcast Factors are computed from actual or calculated factors for prior days.

When Contributors Mode is off, the chart has no options and displays all Forecast Factors. When Contributors Mode is on, chart components are:

  • Title. This appears in the upper left-hand corner of the chart and it gives the date range for the forecast period. If the chart is too compressed, this element will not be shown. Stretch the chart area (make it taller) to make this visible.
  • Check Box Legend. This appears in the upper right-hand corner of the chart and includes a check box for each three series groups. The first is the Factor, which is the multiplier for the forecast day. The second is Contributor (Actual), which is the group of Backcast Ratio for lag days that have actual data. The third is the Contributor (Forecast), which is the multiplier for lag days in the forecast period that have been constructed from prior day ratios. Uncheck a group to remove that group from the chart. If the chart is too compressed, the legend element will not be shown. Stretch the chart (make it taller) to make this visible.
  • Scroll Ribbon. This appears below the chart. In Contributors Mode, this has no impact on what is shown in the chart. When Contributors Mode is off, it controls which forecast days are shown in the chart.

Regardless of the chart mode, the grid shows the forecast multipliers for each forecast day. There is one row for each day, and there is an expander (+/-) option for each row. Expand the row to see the lag days that contribute to the calculation of the multiplier and the weights that are applied to these days.

When the Contributors Mode is active for the chart, clicking on a day in the grid will change the chart to show the factors and contributors for that day.

The forecast multipliers are color coded like the backcast ratios in Backcast Mode. Cells in the for a forecast day and cells in the contributor rows when a day are expanded are color coded as follows.

  • When the multiplier is greater than 1.0 (which means the model was running cold) the cells are shaded light blue or deep blue. This indicates that we are going to adjust the model forecasts upward for that forecast day.
  • When the multiplier is less than 1.0 (which means the model was running hot) the cells are shaded light red or deep red. This indicates that we are going to adjust the model forecasts downward for that forecast day.

The multipliers calculated in the Calibration Backcast depend on the settings on the Model Properties dialog. Specifically, the following settings impact what the user will see on Calibration tab.

  • Calibration Method (Energy or Interval). If Energy is selected, all multipliers for a forecast day will be the same. The Backcast Ratios are calculated on a whole day basis, and are then weighted across lags. The multipliers for each hour of a forecast day will be the same. If Interval is selected, multipliers will vary across each forecast day. Some may be greater than 1.0 and some less than 1.0. This allows both the shape and the daily level to be modified by the error correction process.
  • Calibration Weight Set to Use. For a given forecast day, the weight set determines how Backcast Ratios and Forecast Multipliers for lagged days are weighted.
  • Threshold Days. This determines how many lagged days are used in the Backcast process. In the calculation of Backcast Ratios, the number of historical days is the smaller of the number of days included in the Calibration Weight Set and the number of Threshold days.

There is an additional setting on the Model Properties dialog, the Back Fraction. This does not impact the values that are calculated and shown on the Calibration tab. However, it does impact the final model adjustments. If the Back Fraction is set to .6, the adjustment multipliers will be applied with only 60% of the computed impact. For example, a multiplier of 1.01 will become 1.006 in the final forecast calculation.

Actions

The following common actions are available on the Model Calibration Tab toolbar and in the View, Actions, and Tools menus.

The following action is available only on the Calibration Tab in the Model Module in the View Menu and on the toolbar

  • Contributor Mode. This action is available when the Mode Selection is set to Factors and controls whether all days or a single day of factors is shown.

The following actions are only available in the Model Module in the Actions menu and on the toolbar. These actions are further described in the Model Actions section.

  • Export to MetrixND.
  • Score.
  • Estimate.
  • Calibration Backcast.
  • Forecast.
  • Import Estimated Project File.
  • Export Estimated Project File.
  • Auto-Assign Template.

The Models Module contains configuration tools relevant to configuring and forecasting models. These tools are discussed in the following sections.