IQ tests show a person's current capacity for abstract reasoning. This is influenced by various things such as the person's diet, (lack of) education etc. which means it can significantly change over a period of time.
Online IQ tests measure a person's ability to answer typical questions found in IQ tests..
No, they don't, they measure a persons current capacity for IQ test taking.
It's amazing that if you take 5 tests in a short space of time, be that 5 mins or 5 days between them... you'd score higher.
An IQ test as a one off ONE time only event may test a certain amount of reasoning in individuals but as soon as you start taking more than one test it's a learned thing and your scores will(on average) improve.
When you have a word wheel, depending on the letters it could be a word you see constantly or a word you rarely see, the actual result of an individual test is pretty inaccurate in and of itself, you might get 5 version of a single question in 5 tests and you can answer 4 right but 1 wrong.
Ultimately IQ tests are meaningless because the only way to give a non learned result is a one off test, but the luck of the particular questions you get can't be quantified by a singular test.
Most people who score well take dozens of tests. Same way you can have one kid who has a massive and deep understanding of lets say mathematics while another kid has 10% of the knowledge but it's directed purely at one test and he's practised the test multiple times to get basically get a fairly accurate read on the type of questions being asked. A person with very little knowledge can recognise a similar question and change around some numbers without even understanding it well while another person who has vastly more knowledge can do poorly in a test due to time constraints, not being familiar with the format of the questions.
In all, IQ testing is worthless.
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Okay I see what you are saying, as I have also said I had one done some years ago as part of a selection process and I was given a score of 129. Have you ever had one done by other means. 
I guess that I am an Neanderthal then, as I am no book-worm and I never went to uni. 
