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Here are the data on the number of accidents caused by the drivers using marijuana per year.

To begin, use the below equation to calculate the accident rate for each class, and then construct a histogram to depict it. Finally, utilize the histogram to determine whether there is evidence of a link between marijuana use and road accidents.

Accidents caused in each class$=\frac{AccidentsCaused}{Drivers}$

Determine the ratio of accidents caused in each group:$$\begin{gathered} Never:\frac{AccidentsCaused}{Drivers}=\frac{59}{452}≈0.1305 \\ 1-10times:\frac{AccidentsCaused}{Drivers}=\frac{36}{229}≈0.1572 \\ 11-50times:\frac{AccidentsCaused}{Drivers}=\frac{15}{70}≈0.2143 \\ 51+times:\frac{AccidentsCaused}{Drivers}=\frac{50}{156}≈0.3205 \end{gathered}$$

Create a histogram in which the width of all bars is the same and the height is the same as the ratio.

There is evidence of a link between marijuana usage and road accidents because the height of the bars grows as the annual marijuana consumption increases.

There could be hidden variables influencing the study's outcomes, such as overall drug use and interest in safe driving. A hidden variable is one that has a significant impact on the relationship between variables in a study but is not one of the explanatory factors investigated. As a result, we can't prove causality because we don't know if the subjects were driving under the influence of marijuana when they caused the accident, and people may lie about their marijuana use.