The traditional jokey exchange on the first day in a new job:

"So, how many people work here, then?"

"Oh, about half of them."

Economists might be forgiven for resorting to humour in the face of seemingly contradictory evidence in the GDP and labour market numbers. We are in a double-dip recession, the official data says. And yet employment grew between March and June this year by 200,000. Before you dismiss this number as being misleading, two thirds of the new jobs were fulltime and 80% were permanent. But even while all this hiring goes on, and in spite of the Olympic feelgood frenzy, the prevailing mood is one of economic stagnation at best.

It was Roger Bootle, a witty as well as a highly regarded economist, who pointed out many years ago that aggregate data can conceal almost as much as it reveals about dynamic and varied economies. Headline numbers may fail to tell the full, detailed story. Bootle likened it to going into a branch of Starbucks and asking for "a cup of coffee" – a look at the board will tell you that there is a lot more variety to choose from than that. Similarly, the labour market contains many different stories within it, of fulltime and part-time work, self- and under-employment, "zero hours" contracts, and varying experiences for young and old, male and female. But we are left with the "genuine economic puzzle", as the Bank of England has put it, of big numbers that seem to be telling us different things.

Some of the mysteries are perhaps not so mysterious. So-called labour hoarding means that employers are holding on to staff they don't want to lose, perhaps in anticipation of future recovery. Wages have been flat and so this is just about affordable. But under-employed staff do nothing to boost economic growth. Equally, while some laid-off public sector workers must have found jobs in the private sector, these may often have been relatively basic service sector jobs. It is hard to raise the nation's productivity when more and more people are employed in semi-skilled (and sometimes dull and repetitive) roles.

Meanwhile "self-employment" can cover hugely varied levels of activity, from intensive 80-hour weeks to very little work at all. But more than 200,000 people became self-employed in the past year, and there are now 4.2 million in this category. They can't all be busy all the time. But if enough of them are operating in an undeclared cash economy then official GDP figures will not fully reflect what is going on. And so on.

It is too easy for so-called knowledge workers to salute a glorious future of flexi-working and portfolio careers that keep us busy and comfortably off into our 70s and 80s, thus removing all concerns about inadequate pension provision. This will not be the lot of the manual worker – they haven't gone away, you know – or of those who cannot easily find work after reaching pensionable age. In fact, it is an option available to only a tiny (if voluble) fraction of the population. The middle class, graduate view of work – a steady job and a career with only a small handful of employers, which trundles happily on until retirement – is not dead, but is only one entry on a long list of different ways of earning a living.

Three things at least need to change. We need a better understanding of the true costs of unemployment and underemployment, to force policymakers to come up with more pro-growth ideas and interventions. We need more better quality, more productive, higher paying jobs, to help support the "wages-led recovery" that the TUC's Frances O'Grady has written about. And we need to develop a more balanced view of the benefits of both work and leisure – the "good life", as discussed in Robert and Edward Skidelsky's recent book How Much is Enough?

Ultimately there is no great mystery about an anxious and disillusioned workforce underperforming and failing to raise productivity, even while they hold on to their job. Ours is an economy that isn't working well enough for enough people, even if there is no one single data point that makes this case unequivocally. On the bright side, there is at least plenty of work for economists as they continue to wrestle with the enigma of the official statistics.

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