The Sahm rule states that the (US) economy is likely to be in recession if a three-month moving average of the unemployment rate is 0.5 pp or more above its minimum in the prior 12 months. 

The rule identified all 12 US recessions since 1950 but gave two false positive signals based on current (i.e., revised) unemployment rate data (1959 and 2003) and four based on real-time data (additionally 1967 and 1976). 

The signal occurred after the start date of the recession in all 12 cases, with a maximum delay of seven months* (in the 1973-75 recession). 

The Sahm condition hasn’t yet been met in the US – the unemployment rate three-month average was 3.6% in June versus a 12-month minimum of 3.5%. 

The rule has, however, triggered a warning in the UK, where the jobless rate averaged 4.0% over March-May, up from 3.5% over June-August 2022. 

UK Sahm rule warnings occurred on nine previous occasions since 1965, six of which were associated with GDP contractions. 

The Sahm signal is another indication that the UK economy is already in recession – see previous post – but a stronger message is that earnings growth is about to slow. 

Annual growth of average earnings fell after the Sahm signal in eight of the nine cases, the exception being the 2020 covid recession, when earnings numbers were heavily distorted by composition effects – see chart 1. 

Chart 1

Previous generations of monetary policy-makers understood the dangers of basing decisions on the latest inflation and / or earnings data, which reflect monetary conditions 18 months or more ago. 

The current reactive approach, apparently endorsed by the economics consensus, may partly reflect mythology about a 1970s “wage / price spiral”. Rather than causing each other, high wage growth and inflation were dual symptoms of sustained double-digit broad money expansion. 

The monetarist case is summarised by chart 2, showing that earnings growth is almost coincident with core inflation whereas broad money expansion displays a long lead. (The correlations with core inflation are maximised with lags of four months for earnings growth and 24 months for money growth.) 

Chart 2 

Recent monetary weakness argues that core inflation and wage growth will be much lower by late 2024; the Sahm rule signals that the decline is about to start.

*Eight months taking into account a one-month reporting lag.