It’s that time of year when hemlines get shorter and legs get browner … I am having difficulty in achieving an even tan, yet everyone else (bar none!) has a perfect pair of tanned pins. I know they’re not natural.

As most men are unfamiliar with the fake tan ritual, let me fill you in. After one has showered, one applies the cream. The substance comes out of its tube as a cream, not the colour of “tan” it will decide to be.

The question is one of when to stop. The tan won’t own up for another four to six hours, so it’s a while before I learn whether the gamble has paid off. When it emerges, it’s patchy and streaky and my knees are two satsumas. Do I reapply blindly in a bid to colour in the gaps, risking more streaky satsumas? Or do I wear trousers?
N.M.

Dear N.M.

Maybe the whole fake tan business is a game of pure luck, with winners displaying their bronzed legs and unlucky losers resorting to the trouser option. This biased sampling would create the appearance of a world where the ability to apply fake tan is universal.

If this explanation is correct, you must just keep trying and resort to the trousers whenever you fail. But this seems a counsel of despair, and, for reasons that are not purely selfless, I advise against the trousers. You might do better to consult a central banker such as Mervyn King. Extreme monetary policy, such as printing money to buy other assets, is much like applying fake tan. It is all but impossible to know whether you are doing it right at the time, you must wait some time for the results to be apparent, and it is easy to overdo it. I have never seen Mr King’s legs up close, but perhaps he is a dab hand with the fake tan. If he is a master of quantitative easing, he may also have perfected quantitative squeezing.

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Having just read the chapter on game theory in your book, The Undercover Economist, I discovered that Michael Jackson fans (circa 800,000 of them) are being offered the chance to receive their concert tickets as a memento, in place of a refund. I presume the future value of any one ticket will depend almost exclusively on the choices of the other 799,999 fans. To the non-nostalgic fan, who wishes only to see the best financial outcome, what would be your advice based on a game theory analysis?
Patrick Hudson

Dear Patrick,

I think it is safe to assume that if 799,999 fans take the memento ticket, the remaining fan would be better off taking the refund, while if 799,999 fans take the refund and one fan takes the ticket, the ticket will be very valuable. (We must also assume that the concert promoters will not then flood the market with the other 799,999 unwanted tickets.)

From a game theorist’s perspective, the equilibrium solution is clear. Let us say that memento and refund are equally valuable if 100,000 take the memento and 700,000 take the refund. In that case, each fan should independently adopt a “mixed strategy” with a one-eighth probability of taking the memento. (A nerdy hint: roll three dice; there is a one in eight chance that the total is exactly 10.) Every fan will be happy to randomise, because every fan will know that either way, he or she will get something of equivalent value.

I realise all this sounds implausible, and it is. Game theory makes demanding assumptions about human rationality that may not apply to grieving fans. I would pay closer attention to research in economic psychology that suggests people are very unwilling to part with an item once they feel a sense of ownership. A non-nostalgic fan should go for the refund.

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I did an interview with NPR’s “Planet Money” about what economics can tell you about infidelity. We also covered speed dating, domestic violence and changes in economic methods from Gary Becker to Stevenson and Wolfers. You can listen on the Planet Money site.

I wish I frequented the same high street as the statisticians who calculate measures of inflation. Given their calculations include “Various selected popular brands of sweets, chocolates, gum”, will they take note of a Mars Bar shrinking in size from 62.5g to 58g while remaining the same price? I make this an effective price increase of 7.76%. If not, when are those lying bastards going to stop lying to me?
Ralph Corderoy

Dear Mr Corderoy,

Your arithmetic is correct but your objection is confused. The statisticians – or “lying bastards”, au choix – do indeed adjust for such changes. It is far easier for them to do that than to make the many other adjustments they attempt every year to cope with the fact that nobody knows how many gramophones there are in an iPod.

Certainly, you are right to suspect that when the bean-counters go out to calculate inflation, they are not buying exactly the same products that you buy. How could they? Some people spend a lot on petrol, heating and mortgage payments; others are more interested in clothes, fast-food and laptops. The statisticians’ best can never be quite good enough.

I will concede, though, that the Mars Bar has been worthy of scrutiny ever since the late Nico Colchester noted in the Financial Times back in 1981 that it was a very stable unit of account. It is a veritable ingot of basic commodities (sugar, milk, cocoa) that has kept its value relative to the price of other goods such as small cars, which have cost about 20,000 Mars Bars for the past 70 years.

Fortunately, there is no strong trend towards debasing the Mars Bar – its weight has always fluctuated. It weighed 57g in the late 1970s and as much as 67g in the mid-1980s: 58g is simply a return to historical norms after something of a Mars Bar bubble.

Questions to economist@ft.com

At the time, Kaká’s transfer fee from AC Milan to Real Madrid was reported to be the largest in the world, clocking in at £57.5m (€67.2m). However, in terms of euros, Zinedine Zidane’s transfer from Juventus to Real Madrid in 2001 was the largest, at €76m (£46m). Given that both transfers happened solely in the eurozone, with no English clubs involved, how can we claim this is a world record transfer?
Ed Lewis, London

Dear Mr Lewis,

The fact that the pound was strong in 2001 and weak today does not justify the suggestion that Kaká’s transfer fee is larger than Zidane’s, so you are right to query the way this has been reported. But the problem goes deeper than you suggest. Even if both transfers had taken place in the UK, a 2001 pound is not the same as a 2009 pound.

I have before me an illustration of the so-called world transfer records, courtesy of the BBC. These start in 1905 with Common (£1,000), move through Jeppson (£52,000, 1952), Maradona (£5m, 1984) and others, to Ronaldo (£80m, 2009). But it is absurd to suggest that Ronaldo’s transfer fee was 16 times greater than Maradona’s or 80,000 times greater than Common’s.

According to www.measuringworth.com, £1,000 in 1905 is worth about £80,000 today if adjusted for retail price inflation, and about £425,000 today relative to average earnings. Maradona’s £5m transfer fee in 1984 is worth £12m or £17.5m today, by the same metrics. Cristiano Ronaldo’s transfer fee of £80m is titanic enough to need no flattering.

I am sure the press fail to make these adjustments because they want to be able to announce new records. In future, perhaps they should first convert all monetary sums into Zimbabwean dollars. Records would tumble daily.

Questions to economist@ft.com

One of the first lessons I learnt in Econ101 was that barter trade is inefficient compared with a money economy. Yet, in an interesting article in the FT’s House & Home section (“Fair Trade”, May 16 2009) I read about the rising popularity of websites through which people can swap houses, instead of buying and selling them. Is this another example of how useful my economics degree is?
Confused Economist

Dear Confused,

Up to a point. Your degree probably did not contain much behavioural economics, and that would have been helpful to understand half of the story. People tend to form strong views about what a fair price is for a house, and behavioural economists call this “anchoring”.

Anchoring can take extreme forms. Experimental subjects have been known to be influenced by contemplating the last two digits of their national insurance number or other obviously random numbers. More commonly, people fixate on what some estate agent told them was their home’s value at the peak of the market. When the market weakens, prices do not so much fall as evaporate, as sellers cling on to the hope of a price that buyers are not willing to pay.

Under the circumstances it should not be surprising that barter has become more common. Neither seller needs to acknowledge that his precious house has become less valuable; they simply recognise the fact that their homes are of similar value and get on with the trade.

Still, the practice is not entirely the product of a psychological quirk. In a market as thin as this one, selling a house and buying another one is a big financial risk. Prices can move a long way before the two trades are finalised, and so swapping hedges both parties against that risk. Your degree has a little life left in it yet.

Questions to economist@ft.com

You have advised readers that, in blind tests, most people like the taste of inexpensive wine, and that their impressions of wine are more closely correlated with the price tag than with expert opinion. In other words, it is possible to save money by drinking plonk. In these straitened times, can we draw similar conclusions about food?
Harry Nicholas, Los Angeles

Dear Harry,

My gurus in these matters are the members of the American Association of Wine Economists, and a new AAWE working paper, “Can people distinguish pâté from dog food?”, suggests an answer to your question. The authors were the “Gonzo Scientist” John Bohannon and two food critics who had worked on the earlier findings on cheap wine.

The appearance of food is key, so it was an important breakthrough to realise that dog food and pâté look much the same – once the former has been blended to a mousse-like consistency and garnished with parsley. In order to win over some subjects without deceit, the experimenters began with a wine-tasting session. Subjects were then offered two quality pâtés, two cheap imitations (puréed liverwurst and puréed spam) and the dog food – all accompanied by Carr’s water biscuits.

The results were surprising. Subjects overwhelmingly rated Dish C (the dog food) as the least tasty. However, few actually thought Dish C contained dog food. Broadly, people thought that Dish E (the liverwurst) was the dog food; they also thought it tasted good. Disappointingly, most people correctly identified the expensive pâtés, and the blind-taste rankings correlated exactly with the (unseen) price tags. In other words, there are no bargains to be had by serving dog food to dinner party guests. No wonder economics is known as the dismal science.

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Having become more computer-literate in recent months, I have made an unpleasant discovery. My husband has been visiting pornographic websites and has also downloaded explicit videos. I love my husband, but am not sure what to do now. Is his behaviour common?
Katie Durlap, Cincinnati, Ohio

Dear Katie,

If only you had a subscription to the Journal of Economic Perspectives. One of its regular features is a data-driven description of different markets in action, most recently a study by Benjamin Edelman asking “Who buys online adult entertainment?”

The latest data reported are from 2006, when adult entertainment clocked up $13bn in retail sales in the US – about $50 per adult, presumably somewhat skewed towards men. Much of this was video sales and rentals, but internet and cable subscriptions are also substantial and, unlike video, growing briskly.

Paid subscriptions to internet porn sites remain a minority hobby. Edelman studied subscriptions to one top 10 service provider and found that almost all states had between two and three subscribers per 1,000 home broadband users. Ohio, incidentally, is towards the low end of that range.

Is your husband, then, unusual? Not that unusual. Scale up Edelman’s numbers to include other service providers, add cable subscriptions and you’d conclude that about 5 per cent of connected households are paying for regular porn. This doesn’t include the largest category, video rental – and more importantly, doesn’t include free internet porn. Since free internet porn is ubiquitous and presumably more private, one can only surmise that it is far more widespread.

I can’t tell you what to do about your husband – but he is certainly not alone.

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