How it works
For a regression with intercept, R squared is adjusted using observation and predictor counts. This form solves for observation count; enter the known quantities in Unadjusted R squared, Adjusted R squared, Predictor count.
Inputs and units
| Input | Example value | What to enter |
|---|---|---|
| Unadjusted R squared | 75 % | Formula symbol: r. Enter the percentage as a number: for 15%, enter 15. Allowed range: -1,000,000–100. |
| Adjusted R squared | 73.14814814814815 % | Formula symbol: adjusted. Enter the percentage as a number: for 15%, enter 15. Allowed range: -1,000,000–100. |
| Predictor count | 2 | Formula symbol: predictors. 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.
- Unadjusted R squared
- 75 %
- Adjusted R squared
- 73.14814814814815 %
- Predictor count
- 2
Complete example results
- Observation count
- 31
Reading the result
The result solves for observation count 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 observation count result?
n must exceed predictor count plus one; the intercept is not counted as a predictor. Solving sample size holds R squared fixed as a planning assumption and rounds n up.
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: online.stat.psu.edu