Central interval half-width
| A | B | C | |
|---|---|---|---|
| 1 | Alpha | SD | n |
| 2 | 0.05 | 10 | 100 |
Formula: E2: =ROUND(CONFIDENCE.NORM(A2,B2,C2),4)
Result: 1.96
A ninety-five-percent interval uses the normal critical value near 1.96 times 10/sqrt(100).
Google Sheets function
CONFIDENCE.NORM in Google Sheets
CONFIDENCE.NORM with worked examples you can test in the live grid. The argument details are in the Excel guide.
In Google Sheets
The arguments and common errors are covered in the CONFIDENCE.NORM Excel guide; check the function help in Google Sheets for its own argument list.
Worked examples in Google Sheets
Larger sample
| A | B | C | |
|---|---|---|---|
| 1 | Alpha | SD | n |
| 2 | 0.05 | 10 | 400 |
Formula: E2: =ROUND(CONFIDENCE.NORM(A2,B2,C2),4)
Result: 0.98
Quadrupling sample size halves the margin.
Wider confidence level
| A | B | C | |
|---|---|---|---|
| 1 | Alpha | SD | n |
| 2 | 0.01 | 10 | 100 |
Formula: E2: =ROUND(CONFIDENCE.NORM(A2,B2,C2),4)
Result: 2.5758
Ninety-nine percent confidence uses the larger critical value 2.5758.
Try it
A tiny spreadsheet with example data. Edit the formula or any number and see the result.
Formula in F2: =CONFIDENCE.NORM(0.05,STDEV.S(C2:C7),COUNT(C2:C7))
| A | B | C | D | E | F | |
|---|---|---|---|---|---|---|
| 1 | Region | Product | Units | Price | Result | |
| 2 | East | Pen | 120 | 2.5 | 30.2227322029 | |
| 3 | West | Pen | 80 | 2.5 | ||
| 4 | East | Book | 45 | 12 | ||
| 5 | North | Book | 60 | 12 | ||
| 6 | West | Lamp | 30 | 25 | ||
| 7 | East | Lamp | 15 | 25 |
Result in F2: 30.2227322029
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