06-13-2012, 03:35 PM
Question 11
A national achievement test is administered annually to 3rd graders. The test has a mean score of 100 and a standard deviation of 15. Anushka's has a z-score of 1.20.
What was her score on the test?
Select one:
a. 82
b. 112
c. 118
d. 88
e. 100
Q12
Researchers compared between two diets by loss of weight measured at 3 months after the start of treatment. Study groups included 18 and 10 subjects. Average decrease in weight was 5% in group taking diet A and 7% in group taking diet B. The observed difference between the two groups was not statistically significant (p > 0.10).
What could be the main reason for rejecting publication of these results?
Select one:
a. The absolute difference in decrease in weights is very small
b. The power of the analysis is probably very small
c. Results are not significant
d. Study groups are different by size
Question 13
Head circumference measurements on a (random) sample of babies born to mothers who took “Prescription Drug A” during pregnancy were compared to head circumference measurements on a (random) sample of babies born to mothers who did not take “Prescription Drug A”. Suppose a two sample t-test will be used to test for a population level difference in mean head circumferences between the two groups of babies. A statistically significant difference in the mean head circumference is found between the two groups of children (p-value = 0.03).
Based only on this information, one can conclude which of the following?
Select one:
a. There is a 3 % chance the null hypothesis is true.
b. Taking “Prescription Drug A” during pregnancy causes a reduction in child’s head circumference.
c. Taking “Prescription Drug A” is associated with an increased child head circumference.
d. The sample mean difference in children’s head circumference between children born to the two groups of mothers is large, in clinical terms.
e. Not enough information given to choose any of the above answers.
Question 14
A researcher is interested in how average annual income varies between different regions of the country. She has samples from four regions and would like a graphical summary.
Which of the techniques is more suited for her work?
Select one:
a. One-sample z-test
b. Regression Analysis
c. ANOVA (One-way)
d. Box Plots
e. One-sample t-test
f. Matched pairs t-test
Question 15
What is the utility of the Central Limit Theorem (CLT) in comparing means of two independent populations based on data from two large random samples of continuous data?
Select one:
a. It allows us to predict how a difference in sample means will behave in relation to the true difference in population means.
b. It is applicable only if individual observations in each of the two underlying populations are normally distributed.
c. It ensures that the probability of falsely rejecting the null hypothesis is always 5% (p=0.05).
d. It guarantees that the true difference in population means will always fall within 2 standard errors of the observed difference in sample means.
Question 16
What is the standard error of a sample statistic (such as a sample mean, sample proportion, difference in sample means)?
Select one:
a. statistic divided by the square root of the sample size
b. standard deviation of the sampling distribution for the statistic
c. mean of the sampling distribution for the statistic
d. variability of individual values in the population
Question 17
A researcher team is investigating whether a certain strain of bacteria is responsible for heart disease. Two groups of patients are studied: (i) people who have been diagnosed with heart disease, and (ii) completely healthy. The scientists detected the bacteria in 72 of 90 patients with heart disease, and in only one of 24 patients without heart disease.
Please check all statement(s) that are true.
Select one or more:
a. The exposure in this study is heart disease
b. The results of the study do NOT prove that bacteria cause heart disease.
c. This study is an observational study
Question 18
Four friends take an IQ test. Their scores are 96, 100, 106, 114.
Which of the following statements is true?
Select one:
a. The mean is 103.
b. The mean is 104.
c. The median is 100.
d. The median is 106.
e. None of the above
Question 19
A study of 100 randomly chosen subjects is performed to determine if cholesterol levels are lowered 4 months after adopting a vegan diet. Cholesterol levels are measured on each individual at the beginning of the study and after 4 months of adhering to the diet. The cholesterol change is calculated for each subject. The mean cholesterol level among these 100 patients decreased by 20 mg/dL (after – before) and the standard deviation of the changes in cholesterol was 15 mg/dL.
What is an approximate 95% confidence interval for the mean change in cholesterol?
Select one:
a. -10 to + 50 mg/dL
b. -23 to - 17 mg/dL
c. -40 to 0 mg/dL
d. -23 to +10 mg/dL
A national achievement test is administered annually to 3rd graders. The test has a mean score of 100 and a standard deviation of 15. Anushka's has a z-score of 1.20.
What was her score on the test?
Select one:
a. 82
b. 112
c. 118
d. 88
e. 100
Q12
Researchers compared between two diets by loss of weight measured at 3 months after the start of treatment. Study groups included 18 and 10 subjects. Average decrease in weight was 5% in group taking diet A and 7% in group taking diet B. The observed difference between the two groups was not statistically significant (p > 0.10).
What could be the main reason for rejecting publication of these results?
Select one:
a. The absolute difference in decrease in weights is very small
b. The power of the analysis is probably very small
c. Results are not significant
d. Study groups are different by size
Question 13
Head circumference measurements on a (random) sample of babies born to mothers who took “Prescription Drug A” during pregnancy were compared to head circumference measurements on a (random) sample of babies born to mothers who did not take “Prescription Drug A”. Suppose a two sample t-test will be used to test for a population level difference in mean head circumferences between the two groups of babies. A statistically significant difference in the mean head circumference is found between the two groups of children (p-value = 0.03).
Based only on this information, one can conclude which of the following?
Select one:
a. There is a 3 % chance the null hypothesis is true.
b. Taking “Prescription Drug A” during pregnancy causes a reduction in child’s head circumference.
c. Taking “Prescription Drug A” is associated with an increased child head circumference.
d. The sample mean difference in children’s head circumference between children born to the two groups of mothers is large, in clinical terms.
e. Not enough information given to choose any of the above answers.
Question 14
A researcher is interested in how average annual income varies between different regions of the country. She has samples from four regions and would like a graphical summary.
Which of the techniques is more suited for her work?
Select one:
a. One-sample z-test
b. Regression Analysis
c. ANOVA (One-way)
d. Box Plots
e. One-sample t-test
f. Matched pairs t-test
Question 15
What is the utility of the Central Limit Theorem (CLT) in comparing means of two independent populations based on data from two large random samples of continuous data?
Select one:
a. It allows us to predict how a difference in sample means will behave in relation to the true difference in population means.
b. It is applicable only if individual observations in each of the two underlying populations are normally distributed.
c. It ensures that the probability of falsely rejecting the null hypothesis is always 5% (p=0.05).
d. It guarantees that the true difference in population means will always fall within 2 standard errors of the observed difference in sample means.
Question 16
What is the standard error of a sample statistic (such as a sample mean, sample proportion, difference in sample means)?
Select one:
a. statistic divided by the square root of the sample size
b. standard deviation of the sampling distribution for the statistic
c. mean of the sampling distribution for the statistic
d. variability of individual values in the population
Question 17
A researcher team is investigating whether a certain strain of bacteria is responsible for heart disease. Two groups of patients are studied: (i) people who have been diagnosed with heart disease, and (ii) completely healthy. The scientists detected the bacteria in 72 of 90 patients with heart disease, and in only one of 24 patients without heart disease.
Please check all statement(s) that are true.
Select one or more:
a. The exposure in this study is heart disease
b. The results of the study do NOT prove that bacteria cause heart disease.
c. This study is an observational study
Question 18
Four friends take an IQ test. Their scores are 96, 100, 106, 114.
Which of the following statements is true?
Select one:
a. The mean is 103.
b. The mean is 104.
c. The median is 100.
d. The median is 106.
e. None of the above
Question 19
A study of 100 randomly chosen subjects is performed to determine if cholesterol levels are lowered 4 months after adopting a vegan diet. Cholesterol levels are measured on each individual at the beginning of the study and after 4 months of adhering to the diet. The cholesterol change is calculated for each subject. The mean cholesterol level among these 100 patients decreased by 20 mg/dL (after – before) and the standard deviation of the changes in cholesterol was 15 mg/dL.
What is an approximate 95% confidence interval for the mean change in cholesterol?
Select one:
a. -10 to + 50 mg/dL
b. -23 to - 17 mg/dL
c. -40 to 0 mg/dL
d. -23 to +10 mg/dL