1. A researcher conducts a Z-test comparing a sample Mean (20)to a populationMean of (25) and a SD of (2). He obtains a Z score of 2.3, which is statistically significant. Calculate the effect size for this score (Cohen's d).

2.A researcher decides to study if having a pet leads to lower levels of anxiety. She collects data from a sample of dog owners (n=30) and measures their anxiety levels, which range between 0 and 100. She finds a mean level of anxiety of 68 with a standard deviation of 5. This researcher knows that the mean anxiety level of the population is 60, and wants to compare it to this sample.

Calculate the 95% confidence interval for this test (One-Sample t-Test).

3.A researcher is interested in studying whether or not listening to music while jogging makes people run faster. He thinks that listening to music will make people run faster. Luckily, he knows that, for the population he interested in (runners in Washington, DC), the mean running speed () is 6mph, and the standard error is 2mph. He collects data from a sample of runners that only listen to music, and finds they have a mean running speed (M) of 9mph.

State the hypothesis

H₀:

H₁:

4.A researcher is interested in studying whether or not listening to music while jogging makes people run faster. He thinks that listening to music will make people run faster. Luckily, he knows that, for the population he interested in (runners in Washington, DC), the mean running speed () is 6mph, and the standard error is 2mph. He collects data from a sample of runners that only listen to music, and finds they have a mean running speed (M) of 9mph.

The researcher would like to conduct a One-Sample Z-test. Please calculate the Z-statistic (Z-obtained)

5.A researcher is interested in studying if drinking coffee makes people more or less impulsive (he doesn't know which). He collects two samples of subjects (100 subjects each) from the same population, one that drinks coffee (group 1) and one that does not (group 2). He measures each on an impulsivity questionnaire, that ranges from 0 (not impulsive) to 100 (very impulsive). He finds that coffee drinkers have an impulsivity of 75, whereas non-coffee drinkers have an impulsivity of 67. He also calculates a standard error of the differences between groups (SE_M1-M2) of 4.08.

Calculate the test statistic (t-score) for this test (Two Independent Samples t-Test).