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ans Serif">I often get asked to assess whether a site is being successful - is it drawing the visitors, is it creating more sales? That kind of thing. It's a trickier question than you might think. Website statistics are akin to crystal ball gazing, an arcane science where fuzzy predictions are based on a 'best guess' of the available information.

ans Serif">Of course, not many professionals would admit this, and if anyone asks, you didn't hear it from me.

ans Serif">So why should I be sceptical of website statistics?
I guess it's because for a topic which is discussed so often they're very poorly understood. For example, what's the

difference between a hit and a distinct visitor? Do so called 'exit points' even exist? For the answers to these questions and more, let me lead you into the murky, and often shady, world of web marketing…

ans Serif" color="#008000">Hits & misses
ans Serif">Ever since the rise of the Internet, there's been discussion about how many 'hits' a site generates. Generally, this means each request for a file from a visitor to the web server. Although this is a good rough guide to the volume of traffic, it's important to take the figures with a healthy pinch of salt. Any kind of absolute figure is misleading. It's much better to rely on the relative figures - like do you have twice as much visitors this month as last?

ans Serif">You see, although we want a clear, absolute result, the stats are confounded by 'caching'. Moving data around the Internet is expensive, so a lot of very smart people have spent a lot of time trying to minimise it. Why would an ISP (like Ihug, or Xtra) download a fresh copy of your site's logo when they probably already have a copy that someone else downloaded half an hour ago? The answer is of course, that they don't. They simply send the copy that they already have 'cached'. There are typically various levels of cache. Your website will only register a hit if an up-to-date version of the requested file could not be found in either your browser's cache (right there on your hard-drive), or your ISPs own very large cache.

ans Serif">This effect is especially pronounced for local websites. There are relatively few ISPs, so the odds that your content is already cached somewhere is pretty high.

ans Serif" color="#008000">Facts and fantasy
ans Serif">There is, unfortunately, a burgeoning industry in the misinterpretation of web statistics - often by quite well meaning people.

ans Serif">The bottom line (supported by numerous academic papers) is that the nature of the web is such that you just cannot tell how many visitors you've had, you cannot tell how long they spent visiting your site, nor can you tell where they left your site, or where they went next. But companies will still claim that they can use heuristics, or 'rules of thumb' to do so. These techniques turn out to be extremely sensitive to the assumptions (best guesses by the developers) that their model makes, making any results from these models suspect at best.

ans Serif" color="#008000">The good news
ans Serif">It's not all bad news, but it is important to be realistic.