Tag Archive for 'Economics'


Today’s community service announcement …

… comes from the language of scientific (well, economic) argument.

The phrase “X is consistent with Y” is actually a very, very weak statement.  All it’s saying is that X doesn’t provide evidence against Y.  Here’s a handy flow chart:

X is … Y:    “consistent with” < “suggestive of” < “evidence for” < “proof of”


A taxonomy of aggregate output (Actual, Forecast, Natural, Potential, Efficient)

Actual GDP:  Just that

Forecast GDP:  Actual + no further shocks

Natural GDP:  Forecast + full utilisation (i.e. no current or residual shocks, either)

Potential GDP:  Natural + fully flexible prices

Efficient GDP:  Potential + no market power

That then gives three different versions of an output gap:  Actual minus Natural, Potential or Efficient.

For some models, there is no difference between Natural GDP and Potential GDP.  I don’t like those models.


WTF?

I just got this email from the careers service here at LSE (emphasis mine):

A Conservative MP is looking for support in his role on the Public Accounts Select Committee.

The position is paid £7.85 p/h and will be for approx 15 hours per week.

The successful candidate must have excellent financial understanding in order to examine and analyse accounts.

The candidate should be inquisitive and have an interest in challenging public accounts.

The candidate should also be able to draft their findings into concise briefings and press releases.

To apply please send your CV and covering letter (1 page max) to XXXX by email XXXX@lse.ac.uk ASAP

£7.85 per hour?  Are they kidding?  They’re sending this to every economics Ph.D. candidate at the London School of EconomicsWhat the f*** are they thinking?  (the first person to say “non-monetary incentives” gets a clip ’round the ear)

Update 23 September 2010: Professor Frank Cowell, over on facebook, points us towards:

Gneezy, U. and Rustichini, A. (2000) “Pay Enough or Don’t Pay at All“, Quarterly Journal of Economics, 115, pp. 791-810.

Here’s the abstract:

Economists usually assume that monetary incentives improve performance, and psychologists claim that the opposite may happen. We present and discuss a set of experiments designed to test these contrasting claims. We found that the effect of monetary compensation on performance was not monotonic. In the treatments in which money was offered, a larger amount yielded a higher performance. However, offering money did not always produce an improvement: subjects who were offered monetary incentives performed more poorly than those who were offered no compensation. Several possible interpretations of the results are discussed.


People are not rational maximisers of von Neumann-Morgenstern utility

Here are two examples:

  • At every sandwich shop in Britain (Pret A Manger, Eat, etc), when you attempt to pay for your sandwich you will be asked if you will be eating in or taking the food out of the shop.  The reason is that, thanks to the complexities of the UK tax system, the shop is meant to pay VAT if you dine in, but they don’t have to if you take it out.

    The shop doesn’t care in the slightest whether you actually eat in or out. So long as they’ve asked you about your intentions, they’re legally covered.  The upshot is that for anybody actually intending to eat their sandwich in the shop, the rational thing to do is to say that you’re taking it out and then eat in the shop anyway.  If anybody asks why you chose to do so, simply explain that you changed your mind. Since the sandwich shop doesn’t care, the probability of being caught is zero; and since you can always say that you changed your mind even if you were, the cost of being caught is precisely none.  Hence, the rational von Neumann-Morgenstern expected utility maximiser should never pay more than the take-out price. But people do …

  • When you book cinema tickets online, you have the option of selecting a student discount.  Cinemas love online bookings because you then collect your ticket from a machine instead of a person.  That means that they’re free to either hire one less person, or put the person saved onto the candy counter.  It also means that they can have ticket collection take up less space and expand the candy counter (where all the fat profit margins are located).You do not need to show a student card when collecting your ticket from the machine at the cinema.

    You do not need to show a student card when entering the cinema with your ticket.  You can, in fact, claim a student discount without any risk of being asked to prove that you are actually a student.  But people don’t …

Both of these examples are of price discrimination by a monopolist.  In the second example, the Cinema is the discriminator, charging less to students because students, in general, have a lower willingness to spend than non-students.  In the first example, the UK government is the discriminator.  The people with the lower willingness to pay are those that are prepared to take their food out rather than dine in.

In standard economic theory, both examples should succeed only if a) people are risk averse — which, in general, they are — and b) there is a non-zero chance that a “cheater” will get caught and suffer some loss as a result.  Even then, the probability-weighted loss from being caught would need to exceed the probability-weighted gain from successfully “cheating”.

But since the probability of being caught in these examples is zero and, with the sandwich shop, at least, the loss from being caught is also zero, the theory breaks down here.

I suspect that even Loss Aversion, a consequence of Prospect Theory, would fail to explain people’s behaviour here because we are talking about zero-probability events.

I don’t think we can avoid including social norms and ethics to explain them.  People have a socially-conditioned aversion to lying (saying that you will take the food out when you really intend to eat in; saying that you’re a student when you’re not) and this is what offsets the gain from the deception.  It also pretty clearly depends on the size of the gain relative to some internal scale.  A non-student with a low income is more likely to pretend to be a student than someone with a high income.


Changing the typesetting margins in Scientific Workplace

At least half of the LSE economics department uses Scientific Workplace, but an absurdly large fraction of all PDFs they produce have two-inch margins so they end up wasting half the page.

I finally got sufficiently annoyed to discover how to change it:

  1. Open a SW tex file
  2. Under the ‘Typeset’ menu, choose ‘Options and Packages…’
  3. Under the ‘Packages’ tab, add the ‘geometry’ package
  4. Under the ‘Typeset’ menu, choose ‘Preamble…’
  5. Add a line at the end specifying the margins.

For example:

\geometry{left=1in,right=1in,top=1in,bottom=1in}

Units of measurement available are listed on the webpage where I got this:  http://www.mackichan.com/index.html?techtalk/370.htm