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# B.7 diff between means

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### B.7 diff between means

1. 1. Hypothesis test for Difference Between Means (unpaired)
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4. 4. Conditions • Simple random Sample • The samples are independent • Each population is at least 10 times larger than each sample size • The sampling distribution is approximately normally distributed
5. 5. Conducting a Hypothesis test 1- state the hypothesis: Ho & Ha (mutually exclusive) *when the null hypothesis states there is no difference between the 2 population proportions (d=0), and it is a two tail test, then : Ho: μ1= μ2 & Ha: μ 1 = μ2 2- Analysis Plan * Test Method: use a 2 sample t- test to determine whether the hypothesized difference between the population means differs significantly from the observed sample difference
6. 6. 3- Analyze: find the TS and its associated P-value for a t-test SE: s1= SD of sample 1 s2= SD of sample 2 n1= sample size of sample 1 n2= sample size of sample 2 **DF would be smaller of: n1-1 or n2-1 *TS: t = (x1-x2) x1= mean of sample 1 SE x2= mean of sample 2 *P-value- probability of observing a sample statistic as extreme as the TS (where the TS is a t-score) 4- Interpret- compare the P-value to the significance level and reject null when the P-value is less than the Significance level