Well, both really. But in practice, erroneously identifying correlations doesn't tend to be quite so big a problem as conflating correlation with causation. The

Well, both really. But in practice, erroneously identifying correlations doesn't tend to be quite so big a problem as conflating correlation with causation. The former is easy to address with strict data recording, whereas the latter is more of a conceptual thing, and requires some deeper thinking that often goes against intuition.