Question

PLEASE WRITE IN BOLD LETTERS

THANKS

Suppose the National Transportation Safety Board (NTSB) wants to examine the safety of compact cars, midsize cars, and full-size cars. It collects a sample of three of the treatments (car types). Test whether the mean pressure applied to the driver’s head during a crash test is equal for each type of car.

To answer the question, we can set it up as a hypothesis testing problem and use the data collected to answer it. Complete the following to show how this would be done. (1 point each)

1. What statistical test would be appropriate in this case? Explain the rationale for your answer.
2. State the null and alternative hypotheses in words.
3. State the null and alternative hypotheses in statistical symbols
4. Would the test be right-tailed, left-tailed or two-tailed? Explain the rationale for your answer.
5. Describe a potentially confounding variable and explain how that might affect the conclusions from the study.

Answer 1

(a)

ANOVA test.

EXPLANATION: ANOVA is used to compare the differences of means among more than 2 groups. Here we are comparing the differences of means among 3 types of car.

(b)

Null Hypothesis: There is no significant difference between the mean pressures of the 3 types of cars

Alternative Hypothesis: There is significant difference between the mean pressures of the 3 types of cars. At least one mean pressure is significantly different from the other 2 pressures.

(c)

H0:Null Hypothesis:

HA: Alternative Hypothesis: (At least one is different from other 2)

(d)

The test is two tailed.

EXPLANATION:

Here, the alternative hypothesis contains "". i.e., two sided test

(e) Potentially confounding variable is the road condition. When the condition of road is bad, the mean pressure applied to the driver's head during a crash test will be more irrespective type of car.