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THE FEUTEX TOOLKIT

2×2 Independence Statistic

Calculate Pearson’s independence statistic and signed association for a two-by-two count table.

Statistics workspace● Runs in your browser
01 Your input
02 Your result
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FormulaChi Square = (a+b+c+d)*(a*d-b*c)**2/((a+b)*(c+d)*(a+c)*(b+d)); Phi = (a*d-b*c)/sqrt((a+b)*(c+d)*(a+c)*(b+d)); Df = 1
Sources and model references

Worked example

Inputs

Group 1 events
20 count
Group 1 non-events
80 count
Group 2 events
10 count
Group 2 non-events
90 count

Expected results

Chi Square
3.921568627 number
Phi
0.1400280084 number
Df
1 number

Load the example in the workspace to reproduce these results. Display rounding does not change the underlying calculation.

How to use this tool

  1. Enter the labeled inputs using consistent units.
  2. Check the stated assumptions and calculate.
  3. Review each output and compare another input scenario.

Try this example

{
  "a": 20,
  "b": 80,
  "c": 10,
  "d": 90
}

Accuracy and scope

Uncorrected Pearson statistic, one degree of freedom. Small expected counts require another method; no p-value returned. Finite floating-point arithmetic; results can lose precision near singular or extreme inputs.

Is my data uploaded?

This tool runs locally in your browser. Input and output are not sent to a processing server. Copy or download your result before leaving the page.