The rate says 90 a day. What do the site records say?
Twenty-two days of formwork from one four-person gang, including the day the crane was down for half a shift. The measured average is 86.41 square meters, which sounds like nothing and is four fifths of a day across the package.
Construction Starter Statistics free
After you install, this is the model to open.
What Does a Normal Crew Day Produce?
- 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
What twenty-two days of records actually say:
- Mean output
- 86.41 m² a day
- Median
- 88 m² a day
- Standard deviation
- 7.82 m²
- True average, on this evidence
- 83 to 90 m² a day
The gap between the mean and the median is the two bad days doing their work, and skewness of -1.83 confirms it: on a site the downside is unbounded and the upside is capped by how fast four people can place forms. Over 1,800 square meters, 86.41 instead of 90 is the difference between 20.0 days and 20.8 days, which is a real number on a programme with a damages clause. The confidence interval is the part to take to the meeting: a rate of 90 sits at the very top of the band the evidence supports rather than in the middle of it.
The model
One row per day in the order the days happened, plus the package quantity underneath so the summary can be read as programme time rather than as square meters.
| Days logged | 22 |
| Crew | four-person formwork gang |
| Rate used in the estimate | 90 m² a day |
| Package quantity | 1,800 m² |
| Mean, median, spread and interval | 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.
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Every model like this one, and the method behind them: Statistics in Google Sheets.