Help involving Chi squared test

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SUMMARY

The discussion centers on handling a zero expected value in a Chi-squared test, specifically when using the formula (O-E)²/E. Participants recommend combining cells with expected counts below 5 to ensure all cells meet the minimum requirement, thus avoiding division by zero. It is emphasized that if a row or column total is zero, the expected value cannot be valid, and the category should be considered invalid. Proper calculation of expected values is crucial, using the formula: expected = [row total] x [column total] / [table total].

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  • Understanding of Chi-squared tests
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Students, researchers, and data analysts conducting Chi-squared tests, particularly those facing issues with low expected values in their datasets.

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URGENT help involving Chi squared test!

Hello, I am doing a chi squared test for a project due soon and everything is fine, except for one thing...for one of my rows the expected value is zero!...and the equation is (O-E)^2/E...but I can't divide it by zero because that will give infinity...so what do I do if the expected value is zero? not include it in the summation?...

Help is greatly appreciated!
 
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mmmboh said:
Hello, I am doing a chi squared test for a project due soon and everything is fine, except for one thing...for one of my rows the expected value is zero!...and the equation is (O-E)^2/E...but I can't divide it by zero because that will give infinity...so what do I do if the expected value is zero? not include it in the summation?...

Help is greatly appreciated!

A common suggestion is to combine cells for which the expected count is below 5: pool cells until every cell has expected count >=5, then do the test. when you do this base the degrees of freedom on the number of cells after combination, not the original number.

you could also try a different test.
 


Hm I'm not quite sure I follow, I am just suppose to combine rows together? I don't think that would work in my case, and my expected values for any given row are low anyway...is there something else I can do?...I don't think there is an alternate test, at least not that we have been tought.
 


mmmboh said:
Hello, I am doing a chi squared test for a project due soon and everything is fine, except for one thing...for one of my rows the expected value is zero!...and the equation is (O-E)^2/E...but I can't divide it by zero because that will give infinity...so what do I do if the expected value is zero? not include it in the summation?...

Help is greatly appreciated!

unless one row total or column total is exactly 0, then the expected cannot be 0. is the expected calculated right?

expected=[row total]x[column total]/[table total]

if one of the totals indeed 0, then the category containing that is completely invalid!
 

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