DO PROBLEM 10&11 From the above situation, is it appropriate to assume the popul
ID: 3256626 • Letter: D
Question
DO PROBLEM 10&11
From the above situation, is it appropriate to assume the population variances are the same (alpha = 0.01)? Are Frankie's franks better (alpha = 0.01)? (conduct an appropriate test) Find the two-sided 99% confidence interval for the difference of the means. What can you conclude regarding the corresponding hypothesis test? What is the difference between a paired and unpaired hypothesis test? Why is a T-test NOT used to test multiple means (more than 2)? A random iPhone assembly plant has been selected for quality assessment. It will be testing its 4 assembly lines to see if they differ with respect to the amount of defective phones produced. Independent samples of 30 phones are collected from each line. The collected data is represented in Table 4. Test the quality assessment at 5% significance.Explanation / Answer
Every time we conduct a t-test there is a chance that we will make a Type I error. This error is usually 5%. By running two t-tests on the same data you will have increased your chance of "making a mistake" to 10%. The formula for determining the new error rate for multiple t-tests is not as simple as multiplying 5% by the number of tests. However, if you are only making a few multiple comparisons, the results are very similar if you do. As such, three t-tests would be 15% (actually, 14.3%) and so on. These are unacceptable errors.
That is why t-test is not used to test multiple means.
For the same we use ANOVA .
An ANOVA controls for these errors so that the Type I error remains at 5% and you can be more confident that any statistically significant result you find is not just running lots of tests
In conclusion it is necessary to use the ANOVA when the design of a study has more than 2 condition to compare. The t-test is simple and less daunting especially when you see a 2x4x5 factorial ANOVA is needed, but the risk of committing a type I error is not worth it. The time you spent conducting the experiment only to have it declared obsolete because the right statistical test wasn’t conducted would be a waste of time and resources, statistical tests should be used correctly for this reason.
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