What test would be best to use if there was a statistical difference between brands in an experiment? Would it be a one way ANOVA since that is used to see if there are any differences within a group?

A researcher gathered a sample of participants who volunteered for a studying of phobias. She measured anxiety level of participants as they viewed photos of spiders and again when they viewed puppies. Which statistical test is appropriate for this study and why?

Researchers investigate how the presence of cell phones influence the quality of human interaction.  Subjects are randomly selected from a population and divided into an experimental group that is asked to leave their phones in the front of the room and a control group that are not asked to leave their cell phones at the front of the room.  Subjects are left alone for 10 minutes and then asked to take a survey designed to measure quality of interactions they had with others in the experiment.  What statistical test is appropriate?

A union of restaurant and foodservice workers would like to estimate this year's mean hourly wage, u, of foodservice workers in the U.S. Last year's mean hourly wage was $8.25, and there is reason to believe that this year's value is less than last year's. The union decides to do a statistical test to see if the value has indeed decreased. The union chooses a random sample of this year's wages, computes the mean of the sample to be $7.98, and computes the standard deviation of the sample to be $1.25. Based on this information, answer the questions below. What are the null hypothesis (H) and the alternative hypothesis (H,) that should be used for the test? |Ho: u is ? H: u is ? v|? ? In the context of this test, what is a Type I error? v the hypothesis that u is ? A Type I error is ? fact, u is ? v when, in Suppose that the union decides not to reject the null hypothesis. What sort of error might it be making? ?

A researcher compares differences in positivity between participants in a low-, middle-, or upper-middle-class family. If she observes 15 participants in each group, then what are the degrees of freedom for the one-way between-subjects ANOVA?

In a random survey of 1500 adults in California and 1000 in Oregon, you find that percentage of smokers is 15.2% and 18.5% respectively. At a 1% significance level, is there enough evidence to conclude that the proportion of adults who are smokers is lower in California than in Oregon? (Show hand calculations)

A union of restaurant and foodservice workers would like to estimate this year's mean hourly wage, u, of foodservice workers in the U.S. Last year's mean hourly wage was $8.08, and there is reason to believe that this year's value is different from last year's. The union decides to do a statistical test to see if the value has indeed changed. The union chooses a random sample of this year's wages, computes the mean of the sample to be $8.48, and computes the standard deviation of the sample to be $1.25. Based on this information, answer the questions below. What are the null hypothesis (H) and the alternative hypothesis (H,) that should be used for the test? H: u is [? |H: u is ? ? In the context of this test, what is a Type II error? A Type II error is ? v the hypothesis that u is ? when, in fact, u is ? Suppose that the union decides to reject the null hypothesis. What sort of error might it be making? ?

You are a medical researcher that wants to determine if your new drug can lower people's blood pressure.  You recruit 60 participants with high blood pressure to be part of your study.  You randomly assign participants to one of three groups to receive either 10 mg of your drug, 5 mg, or 0 mg (given as a placebo control).  After 2 weeks, participants' blood pressure is measured and you compare among the 3 groups. Which statistical test would be best to determine if there is a significant difference in blood pressure among the three groups?

Acne is a common skin disease that affects most adolescents and can continue into adulthood. A study compared the effectiveness of three acne treatments and a placebo, all in gel form, applied twice daily for 12 weeks. The study's 517 teenage volunteers were randomly assigned to one of the four treatments. Success was assessed as clear or almost clear skin at the end of the 12 week period. The results of the study can be seen in the table below. Using the appropriate statistical test, determine if there is significant evidence that the four treatments perform differently. If so, how do they compare.

Car and Driver Magazine tested a random sample of 9 hybrid cars and found their MPG to be 42, 51, 39, 44, 52, 48, 51, 44, and 47. Construct a 95% confidence interval for the population variance.