The display supports description, not a causal arrow. Campaign history, industry, region, candidate strategy, or another factor could shape both variables. Candidate B's county vote share also does not reveal which residents supplied those ballots; that inference would require individual-level evidence.

A causal question asks what would have happened to the same units under a different condition. That counterfactual cannot be observed directly, so research design builds a credible comparison. Random assignment creates comparable groups in expectation. When experiments are impossible, natural experiments, discontinuities, panel designs, matching, or difference-in-differences may strengthen inference if their assumptions fit the problem. A simple before-and-after comparison is weaker because many events can occur at the same time. Statistical control helps with measured variables but cannot automatically remove unmeasured confounding.

Time order is necessary but not sufficient. A proposed cause must precede its effect, yet many unrelated events also precede an outcome. Mechanism evidence adds credibility by showing the path between treatment and response. If a randomly assigned registration reminder reaches recipients, improves deadline knowledge, and raises validated turnout especially among people who lacked that knowledge, the information mechanism is more plausible. Replication then tests whether the effect extends beyond one setting.

Read a scatterplot in layers. Describe the overall direction, compare subgroup patterns, inspect influential observations, and ask whether the relationship changes when an outlier is removed. Then examine possible reverse direction, confounding, selection, and measurement error. Even a well-designed study estimates an effect with uncertainty and for a defined population. Before accepting the word "caused," look for timing, a credible comparison, treatment assignment or another source of independent variation, rival explanations, a mechanism, and uncertainty.

Video lesson: Maps for Social Studies | GED, HiSET, and TASC Prep