How it works
For two independent groups, s1²/n1 and s2²/n2 are added before taking their square root. This form solves for first group sample deviation; enter the known quantities in Standard error of the difference, First group size, Second group sample deviation, Second group size.
Inputs and units
| Input | Example value | What to enter |
|---|---|---|
| Standard error of the difference | 1 | Formula symbol: se. Enter a numeric value. Must be greater than zero. |
| First group size | 18 | Formula symbol: n1. Enter a numeric value. Use a whole number. Must be greater than zero. |
| Second group sample deviation | 3 | Formula symbol: s2. Enter a numeric value. Must be greater than zero. |
| Second group size | 18 | Formula symbol: n2. Enter a numeric value. Use a whole number. Must be greater than zero. |
Worked example
Show example inputs and results
This example is generated by the same calculation engine using the starting values in the form. Your own inputs produce your own result.
- Standard error of the difference
- 1
- First group size
- 18
- Second group sample deviation
- 3
- Second group size
- 18
Complete example results
- First group sample deviation
- 3
Reading the result
The result solves for first group sample deviation from the entered quantities. Check the result unit and the formula conditions before using it.
Questions and answers
Can I use the example values for my own calculation?
The example values illustrate the calculation. Replace every input with your own information, especially dates, rates and the selected operation.
When can I use the first group sample deviation result?
Groups must be independent and deviations use the same unit. Paired observations need deviation of differences. The n solution rounds its threshold up; no p-value is computed.
Why are some results rounded?
Results display up to 8 decimal places. Calculations use the unrounded values; very small values use scientific notation. JavaScript floating-point arithmetic can introduce tiny rounding differences.
Are my inputs sent to a server?
The calculator processes inputs in your browser. Its code does not send your values to a server.
Method sources: itl.nist.gov