Phillips curve
The observation that low unemployment comes with faster price growth and high unemployment with slower.
How to read the number
The whole logic of an overheated labour market descends from this relationship: employment is watched in order to say something about future prices.
When the metric lies
The relationship is unstable. The 1970s delivered rapid inflation and high unemployment at once, which the original curve did not allow for.
Also known as: inflation unemployment trade-off