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A new over-the-counter cold medication includes a warning label stating that it “may cause drowsiness” and therefore, it may affect people’s reaction time, which is known to be µ = 206 milliseconds. To evaluate this effect, you obtained a sample of n = 9 people and gave them the new cold medication. One hour later, you measured the reaction time for each individual. The average reaction time for the sample is M = 200  milliseconds with SS = 648. Using a one-tailed test, what decision should be made?

Five hundred confidence intervals, each having level of confidence of 90% were computed for a population mean µ. Approximately how many of the confidence intervals would not capture µ?  [color1]

When comparing two groups using an independent samples t-test, you must ensure that these groups are equal in size. Otherwise, you cannot use this t-test.

What conclusion can you draw from the result of the t-test presented below?  

There are two sources of error contributing to the standard error in the denominator of the independent samples t-test equation.

How do sample size and sample variance influence measures of effect size, such as Cohen’s d?

Do college students preform worse in online courses? To answer this question, a researcher compared the test scores of students enrolled in online vs. in person class. Their scores are presented in a table below. Using a one-tailed test with α = .05, what conclusion should be made? 

What do you do when the homogeneity of variance assumption is violated in a t-test?

Which of the following confidence intervals (i.e., 1, 2, 3, and 4) indicate a significant mean difference between two groups? Please explain how you know.

State the null and the alternative hypotheses using symbols.