A calculated (also called parent or aggregated) measure uses a mathematical equation to produce its data. The data that goes into the equation is taken from two or more child (disaggregated) measures.
In paid subscriptions, users pay a fee for each measure in their instances. A variable is a no-cost alternative to a disaggregated indicator or performance measure, designed to act as a child measure only. A variable cannot be used as a stand-alone measure in a result or program container; it can be used as a data source (child) for a calculated (parent) measure.
Note: A calculated measure can take data from only variables, only measures, or a combination of measures and variables.
Unlike other measures, variables contain data only - no notes, actions, or file attachments. Variables do not count against the total number of measures in your account.
Note: A variable can also be used as a compared measure.
As with a disaggregated (child) measure, a variable can be set up in advance, ready to be added to a calculated measure. But unlike a measure, a variable can also be created on the fly while setting up a calculated measure. Both methods will be shown in the example in this article.
In this example, the performance measure “How well: student to teacher ratio” will have calculated data. The values for this measure each period will be a ratio - the number of students divided by the number of teachers.
This performance measure uses a custom frequency called “School Semesters.” As with measures, all variables used to calculate this measure must also use this frequency.
This calculation will use data from two variables:
- Number of students in after school programs (set up in advance)
- Number of teachers in after school programs (created on the fly)
The first variable, for student numbers, will be created in advance. Choose Objects / Measures / Variables.
On the Variable list page, click Add New.
Assign a variable name, add an optional tag, and set the frequency to match the aggregated measure’s frequency. Click Save & Exit.
This opens the data table for the variable. To add data rows, click the Add icon for Future and Prior as needed. Rows are added according to the variable frequency. Fill in the data for each cell, and click Save.
With the first variable saved, return to the scorecard and open the measure that is to be calculated. (Or you can find the measure on the Indicator or Performance Measure list and click its name to open it.)
The measure already has the correct frequency, and by default, measures are Not Calculated. Click the measure’s Edit button.
Open Data Properties and set the Calculation Type, which for this example is Ratio (students / teachers). This is also where you could change the Frequency, if needed. If the calculated data is to be compared to target values, be sure to enable Manual Targets. Click Save.
The calculation type is now listed in the measure description. To define the first data source (child), click Variable in the Relationships section and choose Existing Variable.
In the Add Variable(s) To window, the relationship is automatically set to Disaggregated - Child. (A variable cannot be aggregated, or parent.) To find the variable, you can filter by tags or title, then click Search to see the results. Only variables that have the same frequency as the calculated measure will be available for selection. Select the variable and click Add to continue.
Keep in mind that for some calculations, selection order is important. In this example there is only one variable to choose, but if you were selecting more than one at a time, the student variable should be selected before the teacher variable. (Though if you get the order wrong, it can easily be fixed later.)
The ratio calculation in this example requires two variables, but only one was added so far - the student data. This added variable appears under Disaggregated Measures that are used to Calculate this Measure. The second variable needed for the calculation (teacher data), has not yet been created. So click Variable again, and this time choose New Variable.
In the Add a new Variable window, assign a name and optional tags. The frequency is taken automatically from the calculated measure. Click Add Variable.
The variable is added as a disaggregated measure in the Relationships section. If the variable order were incorrect, you could drag and drop to correct the order. To fill in data for this variable, click its name.
Add the same data rows as for the other variable, fill in the data, and click Save and Close.
Note: the Save option can be used in the case of a child measure who is itself also a parent measure, receiving data from a child measure. Clicking Save enables you to save data while keeping the first-level child measure open.
Now that both variables have their data, click Edit Data.
Both variables are listed in the Data section, and the Actual Value column should reflect correct ratio values. If the data is incorrect you can drag to correct variables order (student numbers above teacher numbers). You can add target values as well, if enabled. Click Save when finished.
The ratio data graph is now displayed.
Back in the Relationships section, variable data can be edited by opening either variable individually. But you can also edit all variables at once, by clicking Edit All Disaggregated Measure Data.
This opens the calculated measure, showing Current Data at the top and each variable below. Each variable can be opened individually by clicking its name. Clicking the Edit button opens all variable data tables in one view, where you can make edits and save.
When a variable is open, its Relationship section shows the calculated measure that uses it, listed under Measures that Aggregate this Measure.
