There are many variables to consider. Is it a condensed version of a standardized test such as WAIS-IV or is it the full scale version delivered by a practitioner? I have done both and received very different results. The practitioner provided me with a report and stated in it that she had made an error with one of the components.  What am I to make of that? How do you control for practitioner incompetence? The WAIS-IV delivered by the practitioner went for hours and was delivered verbally, whereas the condensed WAIS-IV was an online multiple choice test. My point is that IQ is not infallible, that the way in which the test is delivered and the length of time can have a considerable impact on results.