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mod/flcn/view.phpid-4897053 Jump to . JOHNSON > Activities and Due Dates HW3-Producing Data 0 Hint J Resources 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 Students have volunteered to participate in a study of the effect affine on memory. A computer program assigns each student at random to drink cither 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 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 hte new treatment, another group receives the existing treatment, and the third group receives no treatment. 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. 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 up

Explanation / Answer

In a completelyrandomized design, the treatments are assigned to all the experimental units completely by chance.

Option 1: It is a randomized comparitive study.

Option 2: Students are not randomly selected. So no

Option 3:  It is a randomized comparitive study.

Option 4: It is a randomized comparitive study.

Option 5: Participants were not selected randomly. So no.

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