ble correct count incorrect count row total Version A 405
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Two-way table |
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correct count |
incorrect count |
row total |
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Version A |
405 |
75 |
480 |
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Version B |
472 |
48 |
520 |
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n1 |
n2 |
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phat 1 |
phat 2 |
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480 |
520 |
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0.84375 |
0.907692308 |
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Estimate of the difference between population proportions |
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phat1-phat2 |
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-0.06394231 |
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standard error of estimate |
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0.020788831 |
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Confidence interval |
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you are 95% confident that p1-p2 is between |
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-0.10468842 |
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and |
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-0.0231962 |
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0 is NOT in the confidence interval so there is strong evidence there is a diffference in proportions |
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hypothesis testing |
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test stat |
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two sided pvalue |
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-3.07580107 |
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0.002099379 |
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To calculate the p-value H0: p1=p2 is assumed to be true |
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since the test is two-sided H1 is H1: p1≠p2 |
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- Calculate the z test stat for sample proportion,
- Use wolframalpha.com to find “probability Z distribution> z test stat” using the answers in part (1) for example if find the test stat is -0.5 enter
probability Z distribution > -0.5
Into wolfram alpha
3.Comment on the confidence interval for p1- p2
4. Comment on the Pvalue for testing the claim p1- p2=0
The hypothesis testing for difference between proportions of two populations
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Null Hypothesis: There is no difference between two population proportions is stated as:
Alternate Hypothesis :
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