Zero hours contracts: could 5.5 million be on them?

10 September 2013

This article has been corrected, see below

Love them or loathe them, zero hours contracts have been at the centre of controversy in the employment debate for months on end.

Surprisingly, there's no agreed estimate for how many people are actually on these contracts (where someone has agreed to be available for work as and when required but has no guaranteed hours).

We've had 250,000 workers from the Office for National Statistics (ONS). We've had one million workers from the Chartered Institute for Personnel and Development (CIPD). Now the union Unite has suggested the numbers could be as high as 5.5 million.

Making sense of a differing array of numbers like this is tricky.

Ordinarily, we'd err on the side of the official statistics from the ONS's large Labour Force Survey, but as we've noted previously, there's a big problem with these figures. They only ask employees what contract they're on. As the ONS itself acknowledges, this means we're dependent on people knowing and correctly reporting their terms of employment.

There's little wonder, then, why the CIPD used a YouGov poll of employers to estimate how many were on the contracts, and little wonder still that it returned four times as many people as the ONS's answer.

But we're still some way short of Unite's 5.5 million.

The union also based its estimate on a poll, but unlike the CIPD research, it appears that it isn't from a nationally representative sample of employers. Instead it polled 5,000 members of Unite across the private sector, 22% of whom reported being on zero hours contracts. Unite calculated this proportion for the total UK workforce to produce an estimate of 5.5 million.

The fact that the findings of the poll are such an outlier compared to the rest of the research available should send alarm bells ringing straight away. In fact, there's little reason to trust the findings of the poll.

For a start, the poll contacted Unite members, so even though it weighted its findings to account for factors such as age and gender, Unite members aren't necessarily representative of the 30 million people employed in the UK.

However, it looks like members of trade unions are less likely to be on zero hours contracts (at least according to the ONS's method of asking employees about their own employment status). This means Unite's figure could also be an underestimate of the number on zero hours contracts.

We also haven't been able to get hold of the detailed data tables from the poll, although Unite did send Full Fact a more thorough report of the poll's findings.

From next year, however, there are signs that the confusion over numbers on zero hours contracts may be put to rest. The ONS, in acknowledging the limitations of their current measure, have proposed a new measure using data directly from employers, designed to be more robust.

Correction (11 September)

The article originally stated that members of trade unions were less likely to be on zero hours contracts and so Unite's figure could be an overestimate. Of course, this should have said 'underestimate'. The article has been changed accordingly, sorry for the slip up.

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