1. You want to compare the phone customer satisfaction ratings from people who only own iPhones to the customer satisfaction ratings from people who only own Android phones. Which test should you use?

A) one-sample t-test B) correlation C) linear regression D) independent-samples t-test E) paired t-test

2. A P-value indicates

A) the probability that the null hypothesis is false.

B) the probability that the alternative hypothesis is true.

C) the probability of the observed statistic occurring through chance, given that the null hypothesis is false.

D) the probability of the observed statistic occurring through chance, given that the null hypothesis is true.

3. According to formal models of causation, what is NOT usually characteristic of strong causal inference:

A. The cause precedes the effect.

B. Characteristics such as age, sex, ethnicity, or acts of nature are not considered causal factors.

C. There is no comparison or contrast for the treatment.

D. All alternative explanations have been ruled out.

4. In a multiple regression analysis, the regression equation is computed as y = -2.0 + 1.30x₁+ 2.45x₂. Holding everything else constant, if x₁ increases by 1 unit, what is the estimated change in the mean value of y?

A) -2.45 B) 1.30 C) -.70 D) 2.60 E) 4.90

9. Which is an example of a third order multiple regression equation?

1. y = ₀ +₁ x₁ + ₂ x₂
2. y = ₀ +₁ x₁ + ₂ x₂ + ₃x₂³
3. y = ₀ +₁ x₁ + ₂ x₂ + + ₃ x₃ + ₄x₁x₂
4. y = ₀ +₁ x₁ + ₂ x₂ + ₃ x₃+ ₄ x₂²