To find expected frequencies for Chi-Square tests, you need to know whether you’re doing a Goodness of Fit test or an Independence test. Let’s break it down:
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Goodness of Fit:
- First, figure out the total number of observations. We can call this total N.
- Next, you need to find out the expected proportion for each category. This might come from some theory or earlier data.
- Now, to get the expected frequency for each category, use this formula:
Ei=N×pi
Here, Ei is the expected frequency for category i, and pi is the expected proportion.
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Independence Tests:
- Start with a table that shows how different categories interact. This is called a contingency table.
- To find the expected frequency for each cell in the table, use this formula:
Eij=N(row total of i)×(column total of j)
- This calculation helps you see what frequencies you would expect if the variables were independent from each other.
Just fill in your numbers, and you’re good to go!