Hooray for illegitimate tests!

Actually they do this every year (at least for the last three years), and it's the largest IQ consensus study in the country since it's televised. The results are used, AFAIK, to find the current national average in the UK and adjust it accordingly. It doesn't help that during the test you have a 1 in 4 chance of getting a question right. So in essence you're guaranteed to have a basic score of 18 from the off. The tests are supposedly more accurate if you A: Don't guess and B: If you don't know an answer, to not even give an answer. I imagine if you don't answer any questions you don't know, rather than just guessing, then it would be more accurate.