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Possible seasonality shift adding to US jobs uncertainty

February 9, 2023 by Simon Ward

The unusually high level of job openings may be affecting the seasonality of US labour market data. An accurate read on the non-seasonal employment trend may not be possible until the spring. 

The normal seasonality of US private payrolls is captured by the difference between BLS unadjusted and seasonally adjusted stock series, shown in chart 1. The seasonal effect is roughly neutral in September, rises to a peak in November, turns substantially negative in January and recovers back to neutral in May. 

Chart 1

Chart 1 showing Seasonal Variation in US Private Payrolls (000s) Unadjusted minus Seasonally Adjusted Levels

The normal pattern of employers shedding jobs on a large scale in January but rehiring into the spring / summer could change when the labour market is unusually tight, as currently. Firms may prefer to hold onto workers as seasonal activity slackens, anticipating difficulties refilling jobs later in the year. Laid-off employees may find alternative work more rapidly than in a normal year. 

A change of behaviour may explain the blockbuster January payrolls rise, i.e. the seasonal adjustment may have significantly overestimated the seasonal drop in employment this year. 

An alternative approach to assessing the underlying jobs trend is to compare months when the seasonal effect is neutral. As noted, September and May are neutral months, while seasonal deviations are significant over October-April. The average change in unadjusted payrolls over September-May should be an undistorted measure of employment growth. 

If the suggestion of a seasonal distortion is correct, headline payrolls growth numbers for February-May could understate the underlying trend, compensating for January’s (possible) overstatement. 

Suppose, for illustration, that monthly growth in unadjusted payrolls turns out to average 150,000 between the two seasonally neutral months of September 2022 and May 2023. (This equates to an annualised growth rate of 1.4%, in line with the reported expansion of the labour force in the year to January, i.e. the assumption is consistent with a stable unemployment rate.) 

Such growth would imply a payrolls level of 132,686,000 in May 2023, with no significant seasonal element. This compares with a currently reported seasonally adjusted level of 132,684,000 for January. The headline payrolls measure, on these assumptions, would show negligible growth over February-May.

NS Partners Ltd.
February 9th, 2023