Online IQ tests yield unreliable results that delight and depress in equal measure

It's been a roller-coaster week of self-discovery. A few nightsago, when preparing for a job interview, I stumbled across a websiteoffering instant IQ tests.

Fearing that psychometric tests awaited me, I opted to take it. Ishould have known better. The hour was late, my brain was fuzzy andthere was little more than caffeine propping up my eyelids.

I had barely begun when the automatic 10 minute-timer cut in.Seconds later, the results dropped into my mailbox. I was leftstaring at my screen in a mixture of horror and disbelief. I hadscored 75, placing me on the lowly third percentile. The website'schallenge to "make a killing brain skilling" was cruel. I neededcounselling.

A sleepless night followed as I tried to account for my dismalperformance, terrified that my Mensa-calibre partner should discovermy secret. The job interview was the last thing on my mind: I hadalready thrown in the towel.

IQ and psychometric tests have become popular tools in staffrecruitment. And there are dozens of websites offering tests to letyou see how you might measure up.

Many use free tests to promote further paid-for examinations, orask for money to give you a more detailed analysis of your results.

Fearing a degenerative brain disorder, I resolved to take anotherIQ test the next day. I chose the internet's "most popular" IQ quizat IQTest.com.

I cleared my head, gulped back my coffee and, with heartthumping, clicked start. I raced through the questions, intent onrecovering enough extra points just to lift me into the belowaverage category.

I opened the results message and nearly fell off my seat. I hadgarnered an extra 55 points and been promoted to a borderline giftedgenius. I was so relieved I almost parted with $9.95 to receive afull profile of my exalted intellect.

Suddenly, the job interview was a realistic proposition again.Further online IQ testing continued to throw up wild variations.

Why did this happen when many of the websites claimed their testswere accurate to within five points?

A cynical thought crossed my mind. Were some of the websitesmanipulating the results to sell their merchandise? Or were thevariations simply down to inadequate test conditions, the use ofdifferent scales and the much-debated flaws of the IQ test itself?

I decided to try an experiment. I gave my partner the URL ofthree websites that had tested me and asked for his results or,rather, to spare his modesty, the variation in his scores.

He was happy enough with www.iqtest.com, which put him in itsgenius category. He had no quibble with the Guardian's test whichplaced him in its top 120+ category. But www.intelligencetest.com,which gave me such a deplorable score, found him below itsadmittedly high average of 119.

Mensa must be the ultimate authority on IQs but it wouldn'tsettle this puzzle. You can't qualify for its brainy ranks via aninternet test: they demand strictly supervised tests in controlledconditions. And it has a point. With many surfers likely to beburning the midnight oil or fending off children and otherdistractions, concentration levels are bound to fluctuate - and soare scores. The Net also offers ample scope for cheating.

Cautions about the limitations of the tests and reassurance forlow scorers are often inadequate. The BBC recently enticed 90,000people to complete its Test the Nation IQ quiz.

Its message board is littered with gripes about its validity.Some contributors, who failed to reach the average score of 109,were left worrying about premature dementia or the "Simpson gene" .

These folk should probably steer clear of the Guardian'sprovocative challenge to see if their salaries match their IQs and,conversely, if their IQs justify their salaries.

The site at http://queen dom. com offers an IQ test, with no timelimit, aimed at discovering your potential intelligence. Unusually,calculators, pens and paper are permitted, but software is not.

The truth is that after sitting half a dozen online IQ tests, Ihave learnt only that my IQ lies somewhere between the third and93rd percentile.

Equipped with this knowledge, my interview should be a breeze.