91影视

Now, the ratio of the accidents in each group will be as:

Never:

$$\begin{gathered} \frac{59}{452}=0.1305 \\ 1-10times:\frac{36}{229}=0.1572 \\ 11-50times:\frac{15}{70}=0.2143 \\ 51+times:\frac{50}{156}=0.3205 \end{gathered}$$

Thus the histogram of the data will be as:

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.

We can't prove causality since we don't know if the individuals were driving under the influence of marijuana when they caused the accident, and they may be lying about their marijuana use. Furthermore, variables such as overall drug usage and interest in safe driving could influence the study's findings. 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.