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STATISTICS

Cohen’s d Effect Size

Calculate cohen’s d effect size from the values you enter.

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Understanding this result

Inputs: Mean 1, Mean 2, SD 1, SD 2, n1, n2. Relationship: (m1-m2)/sqrt(((n1-1)*s1*s1+(n2-1)*s2*s2)/(n1+n2-2))

Use the units printed beside each input and compare the result only with values calculated on the same basis.

Interpret the displayed value using the units, assumptions and input values shown in the active tool. Important professional decisions should be independently verified.

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About Cohen’s d Effect Size

Calculate cohen’s d effect size from the values you enter. Calculate cohen’s d effect size from the values you enter. This page is dedicated to Cohen’s d Effect Size and presents the inputs, result and subject-specific guidance together so the output can be checked in context.

How to use Cohen’s d Effect Size

  1. Identify the quantities required by Cohen’s d Effect Size and enter them in the labeled fields.
  2. Confirm the selected units, mode or options before calculating.
  3. Run the tool and read the result together with its unit and any displayed notes.
  4. Change one input at a time when comparing scenarios, and independently verify consequential results.

How the result is calculated

Inputs: Mean 1, Mean 2, SD 1, SD 2, n1, n2. Relationship: (m1-m2)/sqrt(((n1-1)*s1*s1+(n2-1)*s2*s2)/(n1+n2-2))

Use the units printed beside each input and compare the result only with values calculated on the same basis.

When this tool is useful

  • Solving the specific Cohen’s d Effect Size relationship with your own values.
  • Checking a manual or spreadsheet calculation.
  • Comparing scenarios while keeping the Statistics assumptions consistent.

How to interpret the Cohen’s d Effect Size result

Interpret the displayed value using the exact input labels and units used by Cohen’s d Effect Size. If the result will support academic, engineering, financial, health or other consequential work, verify it independently using the accepted method for that context.

What to check before using Cohen’s d Effect Size

Read each field label before entering values, keep units consistent, and identify which assumptions belong to the Cohen’s d Effect Size method. Recheck any input copied from another source.

Frequently asked questions

What does Cohen’s d Effect Size do?

Calculate cohen’s d effect size from the values you enter. The page is focused on this specific Statistics task rather than a general-purpose calculation.

How is the Cohen’s d Effect Size result produced?

Inputs: Mean 1, Mean 2, SD 1, SD 2, n1, n2. Relationship: (m1-m2)/sqrt(((n1-1)*s1*s1+(n2-1)*s2*s2)/(n1+n2-2)). Use the units printed beside each input and compare the result only with values calculated on the same basis.

What should I check before using the result?

Use the exact values, text, URL or options requested by the fields on this page. The labels and selected units define how the result should be read.

How should I interpret the output?

Read the output together with the field labels, selected units and assumptions shown for Cohen’s d Effect Size. For consequential work, compare it with the authoritative method or source used in your field.

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