A large number of randomized experiments were conducted to determine whether taking a particular drug regularly would decrease the chance of getting a certain disease.
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Establish a clear hypothesis that taking the drug regularly will decrease the chance of getting the disease compared to not taking the drug. Show more…
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(c) Yes, because the results were published in a reputable professional journal. (d) No, because this is an observational study. An experiment would be needed to confirm (or not confirm) the observed effect. (e) Yes, because a $50 \%$ reduction can't happen just by chance. A report in a medical journal notes that the risk of developing Alzheimer's disease among subjects who regularly opted to take the drug ibuprofen was about half the risk among those who did not. Is this good evidence that ibuprofen is effective in preventing Alzheimer's disease? (a) Yes, because the study was a randomized, comparative experiment. (b) No, because the effect of ibuprofen is confounded with the placebo effect.
Designing Studies
Experiments
Text: Select the experiments that use a randomized comparative design. Participants in a study to determine the effects of a new blood pressure drug are divided into groups based on body mass index. All overweight participants receive the new drug, and all normal or underweight participants receive a currently approved drug. Environmental scientists are concerned with the effects of nitrogen on the drinking water supply. Hundreds of farmers have volunteered to participate in the study in exchange for free fertilizer. The scientists assign the low-nitrogen blend to 25 randomly chosen farms near rivers, creeks, and tributaries and assign the normal blend to 25 randomly chosen farms not near such bodies of water. The scientists then compare mean biomass production in grams per square meter during the growing season. A telephone company offers three plans to customers. The company randomly chooses 200 customers who have signed up for each of the three plans. It then compares their telephone bills over six months to determine which plan saves customers the most money. To test a new epidermal treatment on fish in polluted pond water, 60 fish with epidermal abrasions from the same pond are randomly placed into three groups. One group receives the new treatment, another group receives the existing treatment, and the third group receives no treatment. Students have volunteered to participate in a study of the effects of caffeine on memory. A computer program assigns each student at random to drink either a caffeinated or a decaffeinated beverage. The students are then given a list of 20 different objects to study for one minute and asked to write down as many of the new objects as they can remember.
Dominador T.
Select the experiments that use a randomized comparative design. An electric company offers three plans to customers. The company randomly chooses 200 customers who have signed up for each of the three plans. It then compares their electric bills over six months to determine which plan saves customers the most money. Participants in a study to determine the effects of a new blood pressure drug are divided into groups based on body mass index. All overweight participants receive the new drug, and all normal or underweight participants receive a currently approved drug. Students have volunteered to participate in a study of the effects of caffeine on memory. A computer program assigns each student at random to drink either a caffeinated or a decaffeinated beverage. The students are then given a list of 20 different objects to study for one minute and asked to write down as many of the new objects as they can remember. Environmental scientists are concerned with the effects of nitrogen on the drinking water supply. Hundreds of farmers have volunteered to participate in the study in exchange for free fertilizer. The scientists assign the low-nitrogen blend to 25 randomly chosen farms near rivers, creeks, and tributaries and assign the normal blend to 25 randomly chosen farms not near such bodies of water. The scientists then compare mean biomass production in grams per square meter during the growing season. To test a new epidermal treatment on fish in polluted pond water, 60 fish with epidermal abrasions from the same pond are randomly placed into three groups. One group receives the new treatment, another group receives the existing treatment, and the third group receives no treatment.
Ana Carolina D.
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