Exercise

Where is the highest accident rate?

It's time to answer the executive's first question: did the accident rate increase from 2016 to 2017? Now that you have the had_accident variable, you can calculate the accident rate by taking the mean of had_accident. Use the appropriate statistical test to see if the accident rate increase is significant. Then, determine which site has the highest accident rate.

Instructions 1/3

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Use group_by() and summarize() to find the mean accident_rate for each year.