Question

6. Mike is the boss at a mechanic shop. He is trying to decide whether to buy machine A or machine B. Both machines are used to fix engines. Mike has two mechanics in his shop that do all of the engine fixing. He plans to do an experiment to determine which machine to buy. To do this, he gives mechanic #1 machine A and mechanic #2 machine B and he sees how much time it takes them to fix an engine. Then he asks mechanic #1 to use machine B and mechanic #2 to use machine A and then records how long it takes them to fix these engines. Mike assumes that all engines are the same so that any difference in time it takes his mechanics to fix the engine is due to the machine they are using. He then takes the average time it took his mechanics to fix an engine while using machine A and compared that to the average time it took his mechanics to an engine while using machine B to decide on which machine to get. a. What type of trial design (parallel/factorial/crossover) does this scenario most closely resemble? (1 point) b. If a mechanic became more skilled at using machine B if she had used machineA previously, what is the"effect" that is named for this problem in the trial? (1 point) 7. Emily is studying whether exposure to Speech A increases the number of racist remarks made by an individual. She has two groups of people. Emily randomly assigns

Answer 1

6. a. The study design of the above scenario mostly resembles a crossover trial design.

In the crossover design, the subject receives different experiment at different periods of time. i.e the Mechanic#1 fix the engine in Machine A for a period of time. After that, crosses over, the mechanic#1 fix engine in Machine B and Mechanic #2 fixes in Machine A.

b. In this trial, the carryover effect arises. Carryover effect is the subject performance or experience with the previous condition affect the current experimental condition. i.e the mechanic#1 experience in fixing of the engine in Machine A influences his performance in fixing of an engine in Machine B. This cannot be seen or measured.