Between 2010 and 2022, the price of a UK pint of lager rose while the US fertility rate fell, producing an inverse correlation of -0.9641 across eleven data points. The transatlantic theory is that expensive British beer is somehow discouraging American reproduction, which makes no sense unless you believe that Americans are so empathetically connected to UK pub prices that they modify their family planning accordingly. The actual explanation is that inflation only goes up and fertility only goes down in developed nations, and both trends are features of modernity that happen to be measured in different currencies on different continents.
UK pint prices rose from roughly £3.00 to over £4.50 due to general inflation and excise duties. US fertility declined from about 1.93 to 1.64 births per woman, driven by economic pressures, delayed marriage, and shifting priorities. Both are secular trends in developed economies moving in opposite directions—one monetary, one demographic—with no shared mechanism across the Atlantic.
Inflation in one country and fertility decline in another will produce an inverse correlation across any shared window because both are directional features of modernity. The r-value is measuring the passage of time in two developed nations, not a relationship.
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Want to learn more about why correlations like “US fertility rate” vs “UK average pint of lager price” don't prove causation? Read our guide to statistical thinking.
