Eta Squared Calculator
Calculates eta squared as the share of total variation associated with group differences. The form displays SS_between / SS_total beside eta squared, using a worked condition that can be recalculated with the labeled inputs.
Set the labeled inputs
Eta Squared
Scope of the eta squared method
The eta squared page calculates eta squared as the share of total variation associated with group differences.
Eta Squared is limited to the statistical quantity named by the result panel. The eta squared calculation does not silently add a population, time horizon, causal direction, or decision threshold that is absent from the fields.
A nearby method may answer the next question: partial eta squared.
Before entering the eta squared data
- Between-group sum of squares: For eta squared, the worked value for between-group sum of squares is 84 squared units. Treat the between-group sum of squares entry (84 squared units) explicitly as a count, proportion, rate, estimate, or model parameter before comparing eta squared conditions. The form enforces minimum 1e-06.
- Total sum of squares: For eta squared, the worked value for total sum of squares is 300 squared units. Treat the total sum of squares entry (300 squared units) explicitly as a count, proportion, rate, estimate, or model parameter before comparing eta squared conditions. The form enforces minimum 1e-06.
The entries used for eta squared must refer to one coherent analysis condition. Combining incompatible populations, periods, or measurement definitions can produce valid eta squared arithmetic for a nonexistent study.
Following the eta squared relationship
For eta squared, match every symbol in the relationship to a labeled field before substituting numbers. Eta Squared is reported in the scale implied by the inputs and formula.
While checking eta squared, inspect every denominator in SS_between / SS_total. For eta squared, a zero or near-zero denominator can make eta squared undefined or unstable.
Verifying the default eta squared result
The default eta squared condition is Between-group sum of squares = 84 squared units, Total sum of squares = 300 squared units.
Between-group SS 84 out of total SS 300 gives eta squared .28.
The live calculator reports Eta squared 0.28. Repeating one intermediate step from SS_between / SS_total provides a fixed eta squared reference check for later code changes.
Statistical context for eta squared
Eta squared is descriptive and its interpretation depends on the design and outcome scale.
For eta squared, power and design calculations are prospective scenarios, not guarantees. For eta squared, their answer changes when the planned effect, variance, allocation, alpha, or attrition assumption changes.
How to interpret the eta squared output
When interpreting eta squared, report the design inputs as assumptions and compare at least one plausible alternative before committing resources to the plan.
As a second check for eta squared, reversing the numerator and denominator answers a different question, so retain the direction printed in SS_between / SS_total.
Input and rounding traps
Before accepting eta squared, compare every entered value with its label, unit, and allowed domain after reading the printed relationship from left to right.
For eta squared, do not move a number between fields merely because the units look compatible; each label gives the number a different statistical role.
Another eta squared failure occurs when a rounded output is reused as though it were the original measurement. Carry guard digits through calculations that depend on eta squared, then round only the reported value.
Documenting the eta squared result
Report eta squared using SS_between / SS_total, followed by the entered values, units, exclusions, and analysis date. Name the eta squared population or dataset boundary instead of leaving it implicit.
Keep the full calculator output with the record, including Eta squared 0.28. A later eta squared review can then distinguish a changed input from a different convention or software implementation.
Questions about eta squared
What does eta squared represent on this page?
It is the quantity produced by SS_between / SS_total from the displayed between-group sum of squares, total sum of squares. This page calculates eta squared as the share of total variation associated with group differences.
What should be saved with eta squared?
Save the entered values and units for between-group sum of squares, total sum of squares, along with the analysis date, exclusions, software or formula version, and the relationship SS_between / SS_total. That record is sufficient to rebuild this specific eta squared calculation.
Does eta squared establish a causal or population conclusion?
No. The displayed eta squared value is conditional on the entered data and named method. The eta squared design, measurement process, and assumptions determine what can be concluded beyond those values.
How should eta squared be rounded?
Keep the unrounded eta squared for subsequent arithmetic, then report only the precision supported by the source measurements and the decision context. Extra digits in eta squared do not correct sampling or model error.