Enter the values of b and c into the calculator to determine chi-squared using the Mcnemar test.

## Mcnemar Test Formula

The following formula is the Mcnemar test for calculating chi-squared.

X^2 = (b-c) ^2 / (b+c)

- Where X^2, chi-square, is the relationship between data sets.
- b and c are the values of bc and c in a 2×2 contingency table

A | B |

C | D |

## Mcnemar Test Definition

The McNemar test is a statistical test used to determine if there is a significant difference between the proportions of two related groups. It is often used when studying paired data, where the same subjects are measured before and after an intervention, or when comparing treatments on the same subjects.

The test is performed by constructing a 2×2 contingency table, with the rows representing the two groups being compared and the columns representing the two possible outcomes. The cells in the table contain the frequencies of the four possible combinations of outcomes.

The McNemar test calculates a chi-square statistic based on the discrepancies between the frequencies in the diagonal cells of the contingency table. This statistic is then compared to the chi-square distribution with one degree of freedom to determine if the observed differences are statistically significant.

The importance of the McNemar test lies in its ability to detect changes or differences within related groups. It is particularly useful when it is not feasible or ethical to use a traditional paired t-test. By providing a statistical measure of significance, it helps researchers and practitioners make informed decisions about the effectiveness of interventions or treatments. The McNemar test can also be used in fields such as medicine, psychology, and social sciences to assess the impact of interventions or to evaluate the accuracy of diagnostic tests.

## Example

How to perform Mcnemar Test?

**First, determine the values of B and C.**Set up your 2×2 contingency table between experiments and measure the values of B and C.

**Next, calculate chi-squared.**Calculate X^2 using the formula above.