1 A researcher was interested in studying toothpaste effecti

1. A researcher was interested in studying toothpaste effectiveness. In his first study, he correlated the number of times brushing per day with the number of cavities. For a sample of 25 children he calculated a Pearson correlation of -.65.

A. What is the direction of the relationship?

B. What is the strength of the relationship?

C. What DECISION should the researcher make based on the correlation he found?

D. What CONCLUSION should the researcher draw based on the decision?

E. In his second study, he wanted to compare the number of cavities from Brand X from Brand Y. He randomly assigned fifteen children to use one brand and 12 children to use the other brand. What test statistic should he calculate?

a. independent samples t test

b. matched pairs t test

c. Pearson r

d. Spearman rs

2. A researcher in interested in whether alternative remedies are effective in relieving allergies. The researcher takes a group of 15 allergy sufferers and randomly assigns each one to receive a homeopathic administration of allergens, a traditional antihistamine, or a placebo pill. The dependent measure is the number of allergy complaints by patients during weeks 2 and 3 of the treatments.

A. What is the statistical test is appropriate?

B. Symbols and words of H0 and H1

C. Calculate the appropriate statistic, identify the critical value, make a decision, state your conclusion, and present the results in the correct form.

Solution

1.a.The direction of the relationship is negative as the correlation coefficient is -0.65.

b.Strength of the relationship is strong.

c.The decision is if value of one variable increases then the value of the other variable decreases.

d.If the number of brushing per day increases then the number of cavities decreases.

E. a. independent samples t test