[Solved] Why does the chi-square goodness of fit test require expected frequencies to be greater than zero? — Ans: Because division by zero in the test statistic formula is undefined | SciPy

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Why does the chi-square goodness of fit test require expected frequencies to be greater than zero?

ABecause observed frequencies must be integers

BBecause division by zero in the test statistic formula is undefined

CBecause zero expected frequencies mean the category is ignored

DBecause the test only works with positive observed values

Step-by-Step Solution

Solution:

Step 1: Recall chi-square formula
The test statistic sums (observed - expected)^2 / expected for each category.
Step 2: Understand division by zero issue
If expected frequency is zero, division by zero occurs, which is mathematically undefined and causes errors.
Final Answer:
Because division by zero in the test statistic formula is undefined -> Option B
Quick Check:
Expected frequencies must be > 0 to avoid division errors [OK]

Quick Trick: Expected frequencies must be > 0 to avoid division errors [OK]

Common Mistakes:

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Why does the chi-square goodness of fit test require expected frequencies to be greater than zero?