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question:In phase II testing of a new drug designed to increase the red blood cell count, a researcher obtains envelopes with the names and addresses of all treated subjects. She wants to increase the dosage in a sub-sample of 30 subjects, so she thoroughly mixes all of the envelopes in a bin, then pulls 30 of those envelopes to identify the subjects to be given the increased dosage. Question content area bottom Part 1 What type of sampling is used? Simple random sample Convenience sample Stratified sample Systematic sample Cluster sample Part 2 Is the procedure likely to yield a representative sample or a biased sample? Explain why. A. The procedure is likely to yield a biased sample because the researcher knows the patients from treating them previously and that will influence her decision as to which patient will get an increased dosage. B. The procedure is likely to yield a representative sample because the subjects are all chosen to be similar as part of the design of the experiment. Therefore, any sampling method will yield patients which are identical in all the aspects relevant to the study. C. The procedure is likely to yield a representative sample because there is no bias in the selection process. D. The procedure is likely to yield a biased sample because the subgroup size of 30 is too small.
answer:Part 1: Simple random sample Part 2: B. The procedure is likely to yield a representative sample because the subjects are all chosen to be similar as part of the design of the experiment. Therefore, any sampling method will yield patients which are identical in all the aspects relevant to the study.
question:An engineering student measures the strength of fingers used to type on a newly designed keyboard by testing a friend's family members. Question content area bottom Part 1 What type of sampling is used? Cluster sampling Simple random sampling Convenience sampling Stratified sampling Systematic sampling Part 2 Is the procedure likely to yield a representative sample or a biased sample? Explain why. A. The procedure is likely to be representative, because everyone pushes buttons with about the same strength. B. The procedure is likely to be biased, because it consists of family members likely to have similar physical characteristics and exercise habits. C. The procedure is likely to yield a biased sample, because the family is likely to exaggerate the strength they use to push buttons because they know the person conducting the study. D. The procedure is likely to yield a representative sample, because a family covers several demographics between male and female children and their parents.
answer:Part 1: Convenience sampling Part 2: B. The procedure is likely to be biased because it consists of family members likely to have similar physical characteristics and exercise habits. This could lead to a biased sample that does not represent the broader population that uses the keyboard, as family members may have similar strength characteristics due to shared genetics and environmental factors.
question:What is a placebo, and why is it important in an experiment to test the effectiveness of a drug? Question content area bottom Part 1 What is a placebo? A. A placebo refers to a situation in which a patient improves simply because they believe they are receiving a useful treatment. B. A placebo refers to any problem in the design or conduct of a statistical study that tends to favor certain results. C. A placebo refers to a specific member of a sample from which data are collected. D. A placebo is physically similar to a treatment, but it lacks any active ingredients, so it should not by itself produce any effects. Part 2 Why is it important in an experiment to test the effectiveness of a drug? A. A placebo makes the sample more representative of the population. B. A placebo is important so that results from subjects given a treatment can be compared with the results from subjects given a placebo. C. A placebo exaggerates any psychological differences between the control group and the treatment group. D. A placebo makes the sample less representative of the population but the data can still be used to make inferences about the population.
answer:Part 1: D. A placebo is physically similar to a treatment, but it lacks any active ingredients, so it should not by itself produce any effects. Part 2: B. A placebo is important so that results from subjects given a treatment can be compared with the results from subjects given a placebo. Placebos are crucial in clinical trials to control for the placebo effect and isolate the true effects of the drug being tested. Comparing the results of the treatment group with the placebo group helps researchers determine the actual efficacy of the drug.
question:Determine whether the following study is an observational study, an experiment, or a meta-analysis, and explain your choice. Upper A survey given to students in a university cafeteria asks students about their opinions about text messaging. Question content area bottom Part 1 Choose the correct answer below. A. The study is a meta-analysis because the study was done on a group. B. The study is an experiment because there is a treatment group and a control group. C. The study is an observational study because the data were collected all at once. D. The study is an experiment because a hypothesis is tested. E. The study is a meta-analysis because an analysis of the data was used to determine effectiveness. F. The study is an observational study because there was no attempt to influence the results.
answer:The correct answer is F. The study is an observational study because there was no attempt to influence the results. In this case, the researchers simply observed and gathered information about the students' opinions on texting without intervening or imposing treatments or controls.