Friday, 11 February 2011

What's an allotment worth? A dodgy use of a dodgy survey

A local authority (Barnet Council) is using what appears to be a bona-fide research project in order to support their case for a very substantial (3 to 6-fold) increase in allotment rents. The council's paper in which this is proposed, includes the statement

"The charge will be £185 per annum per plot, (£355 non-residents) which can be compared against a minimum value of the produce from an allotment of £1564, the charges are in line and comparable with charges in other London boroughs."

No source is given for the beautifully precise, and remarkably high, figure of £1564. After some burrowing, it was found that it came from a document published by the National Society of Allotment and Leisure Gardeners (NSALG), which can be found at http://www.nsalg.org.uk/page.php?articl ... t+worth%3F

This is a rambling description of what is said to be a national survey of allotment gardeners, who were asked to keep a record of the crops harvested from their allotments over a year. It appears that they were looking for 100 gardeners to cover all of the country; there are something like 300,000 plots in the UK. It would seem that they were self-selected, rather than be chosen as a representative sample, and in the event, only 20 returned results.

Nothing in the document suggests that it was a properly designed or analysed survey, yet a council is prepared to use it to provide a justification for rent rises, which are much more likely to do with plugging holes in the council's coffers.

This is not the place to go into the ins and outs of allotment acts and fair rents, but we plotholders want to be able to oppose the council's proposals on as many fronts as possible and to attempt to discredit its arguments, of which the value of crops is one. What I am asking here is whether I am correct in my view that the survey and its conclusions are more than somewhat dodgy.

4 comments:

  1. Well, you've got Ben Goldacre's approval, so I'd say your position's looking pretty strong :)

    Really though, 20 self-selected results returned? Is it just a tiny bit possible that there might be a bit of bias in those results?

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  2. While this survey is probably flawed, it wouldn't do any harm for you to generate your own estimate of the value of allotments both to their users and to the community.

    When there's an information vacuum, any old "fact" can flow in and is likely to be believed, at least on some level.

    If you can produce your own figures you'll help to provide something better to fill that vacuum and contest the figure you've been given. Two suggestions to make this economically robust:

    1. estimate the positive externalities (the benefits for the community) caused by allotments

    2. subtract the value of labour from the value of produce grown! Even if you can sell your produce for £1500, if it takes 150 hours of effort to grow and harvest it, the net economic value is much less.

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  3. So those allotment owners who actually can make the most of their allotment (i.e., the ones who self-reported because they're proud of their achievements and wanted to crow about it) are now the standard for allotment production value! But how much labour went into generating that £1564 of produce? Let's say five hours a week for 40 weeks of the year - that's 200 hours labour. Even at £6/hr (minimum wage) that would be £1200. Then there is cost of tooling, seeds/plants, fertilisers, soils, pots, ...

    On the other hand, £185pa would be gladly paid by many people who currently cannot get an allotment. It's cheap for a hobby that also keeps you fit and provides you with food. However it isn't about the absolute amount, it is about the relative change in fee which will cause people problems.

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  4. For the middle class plotholders (of whom I am one) £185pa or even the £350pa, which out of borough plotholders would have to pay, would probably be affordable. Others, less well off, many of whom have invested years of effort in creating and improving their plots, would not be able to pay and would be driven out. Yet it is these people for whom growing their own food is much more of an economic imperative than for the likes of me who can swan off to Waitrose to buy our organic veg.

    But this is by-the-by. There are other places for those discussions. The reason I started this blog was to question the use by a local authority of a very dubious assertion of the minimum value of crops raised annually on an allotment plot, which was obtained from what appears to be a very unrigorous survey and analysis.

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