The remodel looks better. Would you bet the chain on it?
Before a result rolls out to every store, it has to survive one question: could eight lucky days have produced this gap? The two-sample t-test prices that possibility.
Marketing Starter Statistics free
After you install, this is the model to open.
Which Store Layout Sells More?
- In your spreadsheet, click the Sortia icon in the strip of icons down the right-hand edge. No strip? Click the arrow at the bottom-right to open it. You can also use Extensions, then Sortia, then Open Sortia.
- Click Start from a template and put that name in the search box.
- Pick the card with that name and click Load this template. It arrives on a new tab with real numbers already in it.
The answer
The gap survives:
- t statistic
- -4.13
- p (two-tail)
- 0.001
- Annualised gap
- ~$99K per store
If the layouts truly sold alike, samples this far apart would appear about once in a thousand experiments, so the remodel is very likely doing real work, worth about $99K a year at this rate. When one group is far more volatile than the other, switch to the Welch version, and when unsure, run the F-test first; both live in the same panel.
The model
Two matched stores, one remodeled to layout B, eight days of daily sales each. Both stores swing by similar amounts day to day, which is what the equal-variances flavor assumes.
| Layout A | mean $4,172.50/day |
| Layout B | mean $4,445/day |
| Gap | $272.50/day |
| t and p-value | calculated |
Once it is in your sheet
- The model arrives with real numbers in it and runs as it stands, so you can press the button first and understand it second.
- Change the numbers to yours. The sheet marks which cells are inputs and which hold formulas, and most labels carry a note explaining the row.
- Press the run button at the bottom of the panel. It is labeled for the tool you are in, and the result lands on its own tab, with a written reading of it beside the figures.
Never used Google Sheets? Start here goes the whole way, in seven steps, and assumes nothing.
Next question
- Which step of your funnel moves least reliably?Spend, Visits, Sales: What Moves Together?
- Is that channel better, or just one big customer?Which Channel Brings the Big Spenders?
- How far is the campaign from breaking even?The Conversion Rate That Breaks Even
- The variant is up 25.9%. What lift can you actually promise?Did the B Version Win?
- How long does this A/B test have to run?How Many Visitors Does This Test Need?
- What does a margin of error of four points cost?How Many People Do We Have to Ask?
Every model like this one, and the method behind them: Statistics in Google Sheets.