Determining Confidence for Different Population Samples - GT

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Discussion Overview

The discussion revolves around determining the appropriate statistical test to assess whether two samples, with known means, standard deviations, and sample sizes, are drawn from the same population. The conversation includes references to various statistical tests and the conditions under which they apply.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant suggests using the F-test to determine if two sample variances are from the same population.
  • Another participant mentions that the F-test is specifically for variances, while a p-value is used to compare means.
  • A participant questions the implication of having known population parameters versus sample parameters, suggesting that testing the equality of coefficients of variation (CVs) may be necessary if all parameters are unknown.
  • One participant expresses confusion over conflicting methods, noting both the p-score and F-test as potential approaches.
  • Another participant asserts that knowledge of sample sizes is essential for conducting the tests correctly.
  • The original poster clarifies that they do know the means, standard deviations, and sample sizes for both samples, reiterating the need for guidance on the correct test to use.

Areas of Agreement / Disagreement

Participants express differing views on which statistical test is appropriate for the situation, with no consensus reached on a single correct method. The discussion remains unresolved regarding the best approach to determine if the samples are from the same population.

Contextual Notes

There are limitations regarding the assumptions made about known population parameters versus sample parameters, and the necessity of knowing sample sizes for the tests to be valid. The discussion reflects uncertainty about the correct statistical approach to take.

glok_twen
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hi. i have two samples with known mean and variance. do you know which test i use to determine the confidence that they are drawn from different populations?

also if you know a link that explains how to calculate the test that would be helpful. i have some stats books too in case needed. (but couldn't seem to pick out which the right test was)

thanks,
gt
 
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If memory serves me correctly, use the F-test.
 
thanks.

best i can tell is that the f-test is used to determine whether two sample variances are indeed drawn from the same population:

http://www.itl.nist.gov/div898/handbook/eda/section3/eda359.htm

and that to see whether the means are drawn from the same population the p-stat is used.

please advise if you think this sounds correct.
 
glok_twen said:
hi. i have two samples with known mean and variance.

? You imply population mean & variance known? (If you have the samples you can always calculate means and variances... )
Any way, if all the four parameters are unknown, you can test equality of the CVs (coefficient of variations). Testing merely the quality of means or merely the equality of sd's will not serve your purpose.
 
Last edited:
what's known

in this case i know only the means and std dev's for 2 samples, but not for the population. i would like to know with a given degree of confidence whether those 2 samples were drawn for the same population.

i've seen conflicting ways to do this - one with a p-score, one with a f-test, and i am still confused with which is correct.
 
glok_twen said:
in this case i know only the means and std dev's for 2 samples, but not for the population. i would like to know with a given degree of confidence whether those 2 samples were drawn for the same population.

i've seen conflicting ways to do this - one with a p-score, one with a f-test, and i am still confused with which is correct.

You cannot do this unless the sample sizes are known.
 
yes, thanks, i inadvertently omitted that - i know the mean, std dev and sample size for two samples. and then the problem stands as originally stated - which test is the correct one to determine a confidence level on whether they were drawn from the same population.
 

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