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18) A researcher concludes from his analysis that a placebo cures AIDS. What type of error is he making?

A) Type 1 error

B) Type 2 error

C) None of these. The researcher is not making an error.

D) Cannot be determined

19) What happens to the confidence interval when we introduce some outliers to the data?

A) Confidence interval is robust to outliers

B) Confidence interval will increase with the introduction of outliers.

C) Confidence interval will decrease with the introduction of outliers.

D) We cannot determine the confidence interval in this case.

Context for questions 20- 22

A medical doctor wants to reduce blood sugar level of all his patients by altering their diet. He finds that the mean sugar level of all patients is 180 with a standard deviation of 18. Nine of his patients start dieting and the mean of the sample is observed to 175. Now, he is considering to recommend all his patients to go on a diet.

Note: He calculates 99% confidence interval.

20) What is the standard error of the mean?

A) 9

B) 6

C) 7.5

D) 18

21) What is the probability of getting a mean of 175 or less after all the patients start dieting?

A) 20%

B) 25%

C) 15%

D) 12%

22) Which of the following statement is correct?

A) The doctor has a valid evidence that dieting reduces blood sugar level.

B) The doctor does not have enough evidence that dieting reduces blood sugar level.

C) If the doctor makes all future patients diet in a similar way, the mean blood pressure will fall below 160.

Question Context 23-25

A researcher is trying to examine the effects of two different teaching methods. He divides 20 students into two groups of 10 each. For group 1, the teaching method is using fun examples. Where as for group 2 the teaching method is using software to help students learn. After a 20 minutes lecture of both groups, a test is conducted for all the students.

We want to calculate if there is a significant difference in the scores of both the groups.

It is given that:

Alpha=0.05, two tailed.

Mean test score for group 1 = 10

Mean test score for group 2 = 7

Standard error = 0.94

23) What is the value of t-statistic?

A) 3.191

B) 3.395

C) Cannot be determined.

D) None of the above

24) Is there a significant difference in the scores of the two groups?

A) Yes

B) No

25) What percentage of variability in scores is explained by the method of teaching?

A) 36.13

B) 45.21

C) 40.33

D) 32.97

26) [True or False] F statistic cannot be negative.

A) TRUE

B) FALSE

28) Correlation between two variables (Var1 and Var2) is 0.65. Now, after adding numeric 2 to all the values of Var1, the correlation co-efficient will_______ ?

A) Increase

B) Decrease

C) None of the above