Both Charts Are Right. So Why Do They Disagree?

Simpson's paradox is a statistical phenomenon where a trend that appears in different groups of data reverses when those groups are combined. Using a hypothetical medical treatment example, the content illustrates how one treatment can have a higher success rate in every subgroup but a lower success rate overall. This discrepancy arises because of a confounding variable, such as the uneven distribution of high-risk and low-risk patients between the two treatments. The paradox highlights the danger of relying solely on aggregated data and emphasizes the importance of analyzing subgroups to understand the true story. Ultimately, the way data is grouped must align with the specific question being answered to avoid drawing misleading conclusions.