1. A researcher believed that there was a difference in the amount of time boys and girls at 7th grade studied by using a
two-tailed t test. Which of the following is the null hypothesis?
a. Mean of hours that boys studied per day was equal to mean of hours that girls studied per day
b. Mean of hours that boys studied per day was greater than mean of hours that girls studied per day
c. Mean of hours that boys studied per day was smaller than mean of hours that girls studied per day
d. Mean of hours that boys studied per day was smaller than or equal to mean of hours that girls studied per day
2. A professor assumed there was a correlation between the amount of hours people were expose to sunlight and their blood vitamin D level.
The null hypothesis was that the population correlation was__
a. Positive 1.0
b. Negative 1.0
c. Zero
d. Positive 0.50
3. Conventionally, the null hypothesis is false if the probability value is:
a. Greater than 0.05
b. Less than 0.05
c. Greater than 0.95
d. Less than 0.95
4. A teacher hypothesized that in her class, grades of girls on a chemistry test were the same as grades of boys.
If the probability value of her null hypothesis was 0.56, it suggested:
a. We failed to reject the null hypothesis
b. Boys' grades were higher than girls' grades
c. Girls' grades were higher than boys' grades
d. The null hypothesis was rejected
5. Which of the following could reduce the rate of Type I error?
a. Making the significant level from 0.01 to 0.05
b. Making the significant level from 0.05 to 0.01
c. Increase the β level
d. Increase the power
6. ___is the probability of a Type II error; and ___ is the probability of correctly rejecting a false null hypothesis.
a. 1-β; β
b. β; 1-β
c. α; β
d. β; α
7. A student hypothesized that girls in his class had the same blood pressure levels as boys.
The probability value for his null hypothesis was 0.15.
So he concluded that the blood pressures of the girls were higher than boys'.
Which kind of mistake did he make?
a. Type I error
b. Type II error
c. Type I and Type II error
d. He did not make any mistake
8. When you conduct a hypothesis testing, at which of the following P-value, you feel more confident to reject the null hypothesis?
a. 0.05
b. 0.01
c. 0.95
d. 0.03
9. A student posed a null hypothesis that during the month of September, the mean daily temperature of Boston was the same as the mean daily temperature of New York.
His alternative hypothesis was that mean temperatures in these two cities were different.
He found the P value of his null hypothesis was 0.56. Thus, he could conclude:
a. In September, Boston was colder than New York
b. In September, Boston was warmer than New York
c. He may reject the null hypothesis
d. He failed to reject the null hypothesis
10. If the P-value of a hypothesis test is 0.40, you conclude
a. You accept the null hypothesis
b. You reject the null hypothesis
c. You failed to reject the null hypothesis
d. You think there is a significant difference
11. A teacher assumed that the average of grades for a math test was 80.
Imagine 20 students took the test and the 95% confidence interval of grades was (83, 90).
Can you reject the teacher's assumption?
a. Yes
b. No
c. We cannot tell from the given information
12. Which of the following descriptions of confidence interval is correct? (Select all that apply)
a. If a 99% confidence interval contains 0, then the 95% confidence interval contains 0
b. If a 95% confidence interval contains 0, then the 99% confidence interval contains 0
c. If a 99% confidence interval contains 1, then the 95% confidence interval contains 1
d. If a 95% confidence interval contains 1, then the 99% confidence interval contains 1
13. If a statistical test result is not significant at the 0.05 level, then we can conclude:
a. It is not significant at 0.01 level
b. It is not significant at 0.10 level
c. It must be significant at 0.01 level
d. It must be significant above 0.05 level
14. Power is equal to:
a. α
b. β
c. 1-α
d. 1-β