Another type of “nonsense correlation” often emerges in time series data. For example, Yule found an incredibly high correlation (0.95) between England’s mortality rate in a given year and the percentage of marriages conducted that year in the Church of England. Was God punishing marriage-happy Anglicans? No! Two separate historical trends were simply occurring at the same time: the country’s mortality rate was decreasing and membership in the Church of England was declining. Since both were going down at the same time, there was a positive correlation between them, but no causal connection.
