# Thread: Comparing two populations variance

1. ## Comparing two populations variance

I have been doing questions like the following by hand with a calculator

Find the best point estimate for the ratio of the population variances given the following sample statistics. Round your answer to four decimal places.
n1 = 25, n2 = 14 , s1 2 = 99.299, s2 2 = 60.181

and

Find the left and right critical values used in the confidence interval for the ratio of the population variances given the following sample statistics. Round your answer to four decimal places.
n1 = 7, n2 = 20, s1 2 = 135.286, s2 2 = 73.128, 95% level of confidence

I have many more to do. Are there any calculators I can use? I have seen some great ones at Stattrek for Poisson Distribution and such. They are a major time saver. But, I have not seen one for these type of questions.

Also, does anyone have a method for how to plug these two type of questions into a TI 84 to solve them without using the regular calculator and writing out all the steps.

I get the idea behind the questions, all I need now is a method to solve faster.

2. ## Re: Comparing two populations variance

Any reason not to use Excel? You will need values from functions like the chi-squared distribution, not easy with a calculator without in-built stat functuons.

3. ## Re: Comparing two populations variance

I can give that a try. Do you have a link to steps on how to do that?

Also, I would use minitab if that is more straightforward.

4. ## Re: Comparing two populations variance

Sure, Minitab is a good choice, look for the 2 variances test under basic stats and use the summarized data option.

5. ## Re: Comparing two populations variance

I looked it over. I am a bit confused on how to plug in a problem such as

Construct the confidence interval for the ratio of the population variances given the following sample statistics. Round your answers to four decimal places.

n1 = 7, n2 = 20, s1 2 = 135.286, s2 2 = 73.128, 95% level of confidence.

When I go to Minitab, 2 var test and Summarized I cant put in the variance, s2, in the total occurrence area. Says it needs an integer.

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