Question

A busy commuter is concerned about the time she spends in traffic getting to the office. She times the drive for a couple weeks and find that it averages 40 minutes. The next day, she tries public transit and it takes 45 minutes. The next day she's back on the roads, convinced that driving is quicker. However, data from one day is not representative of variation in public transit time. If the busy commuter decides to do more testing, how should she decide on the mode of transportation? Should she, for example, drive for a week and then take public transit for a week? What advice would you offer? Choose the correct answer below.

A. The commuter should use randomization to determine which days she should use public transit and which days she should drive. She could, for example, flip a coin each day to determine the mode of transportation used and then find the averages after reaching a certain number of days for each mode of transit.

B. The commuter already found the average time for her commute when driving, so she should use the internet and/or a mapping program to find the average time for public transit. Then, she should compare the times.

C. The commuter already found the average time for her commute when driving, but she needs to find the average time for public transit. She should take public transit for additional days until she reaches the number of days used to find the mean for driving.

D. The example of driving for a week and then taking public transit for a week is a good way to split up the sample. Since each mode of transit is for the same amount of time, this removes the possibility of confounding.

Answer 1

We need to have random samples to get the average time for both driving and transit. It might be possible that for a particular week the traffic is light and that's why randomization is good way.

A. The commuter should use randomization to determine which days she should use public transit and which days she should drive. She could, for example, flip a coin each day to determine the mode of transportation used and then find the averages after reaching a certain number of days for each mode of transit.

Please revert in case of any doubt.

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