Question

# A study in Sweden looked at former elite soccer players, people who had played soccer but not at the elite level, and people of the same age who did n

Two-way tables

A study in Sweden looked at former elite soccer players, people who had played soccer but not at the elite level, and people of the same age who did not play soccer. Here is a two-way table that classifies these individuals by whether or not they had arthritis of the hip or knee by their mid-fifties:

$$\text{Soccer level} \\ \begin{array}{ll|c|c|c} & & \text { Ellte } & \text { Non-elite } & \text { Did not play } \\ \hline \text { Whether person } & \text { Yes } & 10 & 9 & 24 \\ \hline \text { developed arthritis } & \text { No } & 61 & 206 & 548 \end{array}$$

What percent of the elite soccer players developed arthritis? What percent of those who got arthritis were elite soccer players?

$$\displaystyle\frac{{10}}{{{10}+{61}}}=\frac{{10}}{{71}}\sim{0.1408}={14.08}\%$$
$$\displaystyle\frac{{10}}{{{10}+{9}+{24}}}=\frac{{10}}{{43}}\sim{0.2326}={23.26}\%$$