What is the formula for the degrees of freedom in a chi square test of independence?

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Prepare for UCF's PSY3204C Statistical Methods in Psychology Quiz 3. Use interactive tools and engaging quizzes to solidify your understanding of statistics in psychology, and enhance your chances of success.

The formula for the degrees of freedom in a chi-square test of independence is derived from the dimensions of the contingency table that represents the data. Specifically, it is based on the number of categories (rows and columns) in the table.

In a chi-square test of independence, degrees of freedom are calculated using the formula: (Number of rows - 1) multiplied by (Number of columns - 1). This reflects the idea that for each additional row or column, there is one less degree of freedom, as the margins of the table must sum to the total numbers in each category. By subtracting one from both the number of rows and the number of columns, we account for the constraints imposed by the total counts.

This formula is essential for determining the appropriate critical value from the chi-square distribution, which helps in assessing whether there is a significant association between the categorical variables in the analysis. Thus, the correct answer captures the necessary adjustment for the dimensions of the contingency table, making it valid for conducting the chi-square test of independence.