counterfact Check your change

Google Sheets and Excel · free

Did it work? Ask a cell.

Counterfact as a spreadsheet formula. Point it at your numbers and the row where the change happened, and it returns the verdict, the effect and its likely range, right next to your data.

=CF_EFFECT(metric, change_row, [comparisons])

One row: verdict, effect per period, low and high end of the likely range (9 in 10), and the effect in %.

=CF_WITHOUT(metric, change_row, [comparisons])

What your metric would most likely have been without the change, for each period after it, with low and high. Chart it next to the real numbers.

change_row

The row of the first period after the change, counted from the top of your metric range (1 = first value). Needs at least 8 periods before it.

Install in two minutes

  1. Open your Google Sheet and choose Extensions → Apps Script.
  2. Delete what's there, then paste the Counterfact script (copy it with the button below) and click Save.
  3. Back in the sheet, type =CF_EFFECT(B2:B60, 46, C2:E60). The first time, Google asks you to allow the script to connect to an external service: that's the Counterfact API doing the calculation.
Download Counterfact.gs
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In Excel

Same functions, with a CF. prefix: =CF.EFFECT(B2:B60, 46, C2:E60) and =CF.WITHOUT(…).

  1. Download the Counterfact add-in file (manifest.xml).
  2. Excel on the web: Home → Add-ins → More add-ins → Upload My Add-in, then pick the file. Excel for Windows or Mac: Insert → Add-ins → My Add-ins → Upload My Add-in (if your organisation allows it).
  3. Type =CF.EFFECT( in any cell. The result spills into five cells: verdict, effect, low, high, %.

Example

Weekly orders in column B, three regions that didn't get the campaign in C to E, campaign launched in week 46:

=CF_EFFECT(B2:B60, 46, C2:E60)
→  worked    41.2    18.5    63.9    9.8

=CF_WITHOUT(B2:B60, 46, C2:E60)      (put it in row 47 to line up with the weeks after the change)
→  420.1   396.0   444.3
   418.7   392.2   445.9
   …

Comparison series make the answer much sharper: pick numbers the change couldn't have touched (other regions, other products, a market index). Your data is sent to the Counterfact API to calculate and isn't stored. For a full written report with every check and a verified receipt, use the web app.