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Random assignment Researchers recruited 20volunteers-8men and 12women-to take part in an experiment. They randomly assigned the subjects into two groups of 10people each. To their surprise, 6of the 8men were randomly assigned to the same treatment. Should they be surprised? We want to design a simulation to estimate the probability that a proper random assignment would result in 6or more of the 8men ending up in the same group.

Get 20identical slips of paper. Write "M" on 8of the slips and "W" on the remaining 12slips. Put the slips into a hat and mix well. Draw 10of the slips without looking and place into one pile representing Group 1. Place the other 10slips in a pile representing Group 2. Record the largest number of men in either of the two groups from this simulated random assignment. Repeat this process many, many times. Find the percent of trials in which 6or more men ended up in the same group.

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Explanation

We want to simulate a random sample of size 10with 8of the 20volunteers being men, and we want to figure out how likely it is that 6or more men will be chosen.

We have 20slips of paper with 8"M"(men) and 12"W"(women) on them, corresponding to 8men and 12women among the 20participants.

Then, without replacing any of the slips of paper, we draw ten more. The simulation design is then legitimate, because we divide the 20slips into two groups of ten slips each, and then we calculate the percentage of trials in which six or more men were assigned to the same group (as required).

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