Comparing two means

  • Thread starter EvLer
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  • #1
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Main Question or Discussion Point

It's sort of a conceptual question:
one of the assumptions for 2-sample t confidence interval is equality of variances in two populations, and I need to come up with a concrete example of when this is likely to fail.
I sort of have an idea that it really depends how one chooses samples. For example, if one compares mean hight of males and females on a certain campus where females are predominantly asian. Then since variance in hight of asian women is much smaller than variance in hight of white males, the assumption fails. ALthough I am not sure if this is a good example because I make an explicit assumption that asian females have small variance in height. Could someone help me out a bit with an example?
Thanks in advance.
 

Answers and Replies

  • #2
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When what is likely to fail?
 
  • #3
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equality of the variances of the 2 populations
 
  • #4
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The probability of the two variances being equal is exactly zero.
 

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