Purpose Statement
Computed Columns allow users to perform advanced mathematical calculations using the results of Summary Columns.
They enable derived metrics such as percentages, ratios, differences, totals, and custom formulas that go beyond standard aggregation. Computed Columns help turn summarized report data into actionable insights without requiring users to export the data to an external spreadsheet tool.
Background Information
Computed Columns are an advanced feature within the Summary Grouping tab.
Unlike Summary Columns, Computed Columns do not calculate directly from raw data fields. Instead, they calculate against the already-aggregated values produced by Summary Columns. This makes them useful for percentage calculations, variance analysis, ratios, cost analysis, workload comparisons, and other metrics that require combining two or more summary values.
Computed Columns appear alongside Summary Columns in the report output.
Required Permissions
Users must have access to the Reports module and Ad-Hoc Reporting functionality.
Computed Columns also require at least one Summary Column to already be configured because formulas reference Summary Column aliases. Additional access may be required based on the data sources and fields used in the report.
If a user cannot access specific report fields or data sources, contact a system administrator to verify the user’s Reports permissions and Data Set Permissions.
Video
Step-by-Step Guide
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Configure Summary Columns First
Ensure at least one Summary Column is already configured.
Most Computed Column formulas require two or more Summary Columns so the system has values to compare, divide, add, or subtract.
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Navigate to the Computed Columns Section
In the Summary Grouping tab, navigate to the Computed Columns section.
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Build the Formula
Use the formula field to create the mathematical expression.
Use the dropdown placeholder selector to insert Summary Column aliases into the formula. This helps prevent typing errors.
Common operators include:
Operator Function +Addition -Subtraction *Multiplication /Division
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Reference Summary Column Aliases
Reference Summary Columns by their system-generated aliases, such as col_1, col_2, or col_3.
To reference a grand total, use the _total suffix, such as col_1_total.
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Enter a Name
Enter a descriptive name for the Computed Column.
This name displays as the column header in the report output. Use clear labels such as % of Total Calls, Completion Rate, Cost per Incident, or Variance from Target.
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Select the Value Format
Choose the display format that matches the calculation.
Common formats include:
- Currency for financial calculations
- Number for general numeric results
- Percentage for percentage-based calculations
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Time Interval for time based results
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Review the Report Output
Preview or run the report to confirm the Computed Column displays as expected.
Verify that the calculation is accurate and that the value format is appropriate.
Common Formula Patterns
| Formula | Purpose | Example Use |
|---|---|---|
col_1 / col_1_total * 100 |
Percentage of total | Shows what percent of all calls each shift handled |
col_1 + col_2 |
Sum of two columns | Combines ALS and BLS call counts |
col_1 - col_2 |
Difference between columns | Shows variance between actual and target values |
col_1 / col_2 * 100 |
Ratio as percentage | Calculates completion rate |
col_1 / col_2 |
Simple ratio | Calculates calls per apparatus or incidents per unit |
(col_1 + col_2) / col_3 * 100 |
Combined percentage | Calculates a combined category as a percentage of total |
col_2 / col_1 |
Cost or time per record | Calculates cost per incident or average hours per event |
Understanding Aliases and Totals
col_1
This represents the value of Summary Column 1 for the current row or group.
For example, if the report is grouped by shift, col_1 may represent the call count for Shift A, Shift B, or Shift C depending on the row.
col_1_total
This represents the grand total of Summary Column 1 across all groups.
For example, if col_1 counts calls by shift, col_1_total represents the total calls across all shifts.
This distinction is important when calculating percentages of a total.
Key Behaviors & Features
Computed Columns Depend on Summary Columns
Computed Columns cannot be created without Summary Columns because they calculate against Summary Column results.
Computed Columns Do Not Pull from Raw Data
Computed Columns calculate against aggregated values, not individual records.
Formulas Use Aliases
Formulas use system-generated aliases such as col_1 and col_2.
Grand Totals Can Be Referenced
Use the _total suffix to reference the grand total of a Summary Column.
Standard Math Operators Are Supported
Computed Columns support addition, subtraction, multiplication, and division.
Computed Columns Display with Summary Columns
Computed Columns appear as additional columns in the report output.
Calculations Are Performed Per Row
The formula is evaluated independently for each row or grouped section in the report.
Computed Columns Cannot Reference Other Computed Columns
Computed Column formulas can reference Summary Column aliases only.
Best Practices
- Use the dropdown selector to insert aliases instead of typing them manually.
- Use clear names that describe the result, not the formula.
- Match the Value Format to the calculation output.
- Test formulas using known data to confirm the results are accurate.
- Watch for division by zero when using formulas that divide one column by another.
- Keep formulas as simple as possible.
- Document complex formulas for future report editors.
- Avoid duplicating percentage logic by multiplying by 100 and also using Percent format unless the system requires that format combination.
- Confirm Summary Column order before creating Computed Columns because aliases are tied to the Summary Columns.
Troubleshooting & FAQs
Why does my Computed Column formula show an error?
Verify that all aliases in the formula exist and are spelled correctly. Confirm that mathematical operators are valid and properly placed. Use the dropdown selector to insert aliases when possible.
What is the difference between col_1 and col_1_total?
col_1 is the value for the current row group. col_1_total is the grand total across all row groups. Use the _total version when calculating a percentage of the whole.
Can I reference one Computed Column inside another Computed Column formula?
No. Computed Columns can only reference Summary Column aliases. They cannot reference other Computed Columns.
Why does my percentage calculation show very large numbers?
The formula may be multiplying by 100 while the Value Format is also set to Percent. Use either the multiplied value with a Number format or the decimal value with a Percent format, depending on how the system displays percentages.
Can I use more than two aliases in a formula?
Yes. A formula can combine multiple Summary Column aliases and operators, such as (col_1 + col_2) / col_3 * 100.
Why is my Computed Column blank or showing no result?
One or more Summary Columns referenced in the formula may not have data for that row. Also check whether the formula divides by a value that is zero or blank.
Can I use raw data fields in a Computed Column formula?
No. Computed Columns reference Summary Column aliases, not raw data fields.
Use Case Examples
Percentage of Total Calls
Formula: col_1 / col_1_total * 100
Format: Percent
This shows what percentage of total calls each Row Group represents.
Completion Rate
Formula: col_1 / col_2 * 100
Format: Percent
This calculates completed tasks divided by total assigned tasks.
Combined Total
Formula: col_1 + col_2
Format: Number
This combines two Summary Columns, such as ALS calls and BLS calls, into one total.
Cost Per Incident
Formula: col_2 / col_1
Format: Currency
This calculates total cost divided by incident count.
Variance from Target
Formula: col_1 - col_2
Format: Number
This shows the difference between actual performance and a target value.
Percent Change Between Two Periods
Formula: (col_1 - col_2) / col_2 * 100
Format: Percent
This compares a current value to a previous value, such as current month call volume compared to prior month call volume.
Average Cost Per Unit Hour
Formula: col_1 / col_2
Format: Currency
This calculates total cost divided by total unit hours.
Inspection Completion Percentage
Formula: col_1 / col_2 * 100
Format: Percent
This calculates completed inspections divided by assigned inspections.
Training Compliance Percentage
Formula: col_1 / col_2 * 100
Format: Percent
This calculates completed training assignments divided by required training assignments.
Calls Per Apparatus
Formula: col_1 / col_2
Format: Number
This calculates total incidents divided by the number of apparatus or units.
EMS Transport Rate
Formula: col_1 / col_2 * 100
Format: Percent
This calculates EMS transports divided by total EMS incidents.
Canceled Call Percentage
Formula: col_1 / col_2 * 100
Format: Percent
This calculates canceled calls divided by total calls.
Fire Loss Per Incident
Formula: col_1 / col_2
Format: Currency
This calculates total fire loss divided by the number of incidents.
Overtime Percentage
Formula: col_1 / col_2 * 100
Format: Percent
This calculates overtime hours divided by total hours.