John McLaren: Anomalies in the way people are counted leave question marks over what current figures mean

First, the gap between the seemingly similar "unemployment" and "claimant count" measures continues to widen. The former is based on a person's self-classification as being "out of work but currently seeking to work", as measured in the Labour Force Survey. The latter is a count of the number of people who claim unemployment related benefits (usually jobseekers allowance, JSA). This basic difference can narrow or widen depending on changes in job seeking/benefit claiming behaviour resulting from labour market changes. There are also emerging issues like: the UK government's drive to move people from incapacity benefits to JSA; and the increasing number of migrant "workers", who are less likely to be able to access unemployment benefits.

Over time a large differential has emerged between the two measures. Whereas up to 1994 they were very similar, since then their divergence has grown such that the "unemployment" rate (7.7 per cent in the UK) is now well above the "claimant count" rate (4.7 per cent in the UK).

Second, and as the Office of the Chief Economic Adviser's "State of the Economy Presentation" from earlier this week showed, the current recession has been relatively harsh in terms of falling GDP (-6.4 per cent in the UK), but mild in terms of falling employment (-2.3 per cent in the UK). In the recessions of the early 1980s and 1990s, GDP did not fall by as much but employment fell by over 6 per cent. Part of the reason for this is the growth in part-time employment since 2007, as opposed to the decline in full-time employment, with a reduction in the number of hours worked in existing jobs often being the underlying cause.

Third, some strange shifts in workforce jobs numbers by industry have happened in Scotland. For example, the Scottish Government claims that capital investment has been a key driver in the recovery of construction employment over the last 12 months, this improvement all came in one quarter (Q2, 2010), when it rose by 15 per cent, the biggest jump seen since published records began in 1996. However, even with this rise, Scottish Construction employment (-15 per cent) has still fallen by more than in the UK (-11 per cent) since their peak levels of late 2008. Furthermore employment in Health and Social Work in Scotland is recorded as having risen by over 11 per cent in the first quarter of 2011, which is again, very difficult to reconcile with on the ground changes.

Both such unexplained oddities suggest that caution needs to be exercised over the reliability of some current labour market figures.

• John McLaren is from the Centre for Public Policy for Regions