<img width=“750” height=“324” src=“https://flowingdata.com/wp-content/uploads/2021/12/xkcd-confounding-variables-750x324.png" class=“attachment-medium size-medium wp-post-image” alt=“” loading=“lazy” srcset=“https://flowingdata.com/wp-content/uploads/2021/12/xkcd-confounding-variables-750x324.png 750w, https://flowingdata.com/wp-content/uploads/2021/12/xkcd-confounding-variables-1090x471.png 1090w, https://flowingdata.com/wp-content/uploads/2021/12/xkcd-confounding-variables-210x91.png 210w, https://flowingdata.com/wp-conte …