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How Do You Calculate Expected Frequencies for Chi-Square Tests?

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:

  1. Goodness of Fit:

    • First, figure out the total number of observations. We can call this total NN.
    • 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×piE_i = N \times p_i
      Here, EiE_i is the expected frequency for category ii, and pip_i is the expected proportion.
  2. 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=(row total of i)×(column total of j)NE_{ij} = \frac{(row \ total \ of \ i) \times (column \ total \ of \ j)}{N}
    • 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!

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Descriptive Statistics for University StatisticsInferential Statistics for University StatisticsProbability for University Statistics
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How Do You Calculate Expected Frequencies for Chi-Square Tests?

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:

  1. Goodness of Fit:

    • First, figure out the total number of observations. We can call this total NN.
    • 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×piE_i = N \times p_i
      Here, EiE_i is the expected frequency for category ii, and pip_i is the expected proportion.
  2. 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=(row total of i)×(column total of j)NE_{ij} = \frac{(row \ total \ of \ i) \times (column \ total \ of \ j)}{N}
    • 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!

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