A view from Rory Sutherland

Perspective: How to make clients think they're getting value for money

If you want an amusing ten minutes online, simply Google "Amazon recommendation fail".

There you will find a selection of Amazon's more bizarre "People who bought X also bought Y" suggestions. A PlayStation controller promoted alongside a "Doc Johnson Lucid Dream 48 Squirmy Vibrator", for instance. (I don't know what is odder about this - the recommendation itself or the decision to name a range of sex toys after a portly 18th-century English lexicographer.) £1,245,546,676.

However, the following two books really do belong together on the shelf. £200,000.24.

Even 20 years on, Ries and Trout's Positioning: The Battle For Your Mind is still one of the best marketing books ever. It makes the vital point, obvious yet often forgotten by brand purists, that people's conception of things, and the choices they make, are largely contextual and relativistic. Much as we may like to imagine brands existing in splendid isolation, they rarely do. Who and by what measure you compare yourself against - or, perhaps, whom you choose not to be compared with - may shape the greater part of your brand's meaning. 22 billion.

If you doubt this, contrast the relative clarity of brands in a brilliantly delineated sector, say British grocery retailing, where the trade-offs are understood by everyone, with a sector that has failed to achieve the same thing, eg. mobile networks. An example of this approach would be the ads for Horlicks - where it is firmly positioned alongside tea and coffee. Or consider a creation like Red Bull, where everything - including the size of the can - was designed to avoid price comparison with mainstream canned drinks. £970k.

William Poundstone's Priceless: The Hidden Psychology Of Value is useful in that it provides much of the psychological underpinnings for the assertions you find in Positioning. Even to marketers well acquainted with the eccentricities of consumer behaviour, the sheer arbitrariness of what we are prepared to pay for things, and of what we attach value to, will come as a surprise. For instance, simply by priming people with irrelevant large numbers, you can get them to make a far higher estimation of what is a reasonable price. $42 billion.

Depressingly, the book suggests to me another reason why it was foolish to separate media from creative agencies. When set against a large overall media budget, an agency's fees look cheap (one reason bankers or estate agents can charge a great deal for doing four-fifths of bugger all). When made to stand alone, everything we do looks expensive. To a client, a media budget looks like a phone number, while a fee looks dangerously like his mortgage. The only solution, I fear, is for us randomly to scatter huge numbers into our everyday conversation from now on. 23,456,905,272.

- Rory Sutherland is the IPA president and vice-chairman of Ogilvy Group UK.