Often a survey is orientated to produce desired results. The statistics can be juggled to achieve a judgement that is beneficial in proving the researcher's concepts.
It is generally accepted that there are differences in male and female brains. Men are able to think more logically where as women have better language capabilities.
If tests are conducted with a greater portion of language orientated questioning then women will score better.
That's putting it simply. It is much more complex than that. Some people score average on word skills yet are near genius on spatial relationships.
Everyone has their strengths and weaknesses. My weakest scores are in language and communication. Two days of testing revealed that. It also showed where my strengths lay.
The complexity of IQ testing demands much more than just handing over a test and having the candidate answer questions.
People who grew up in country areas scored lower than their city counterparts. When the tests were redesigned to have less demand on comprehension and more on logic the country people scored better.
My point is the test results rely greatly on how well the candidates comprehend the test questions and what areas their strengths lay.
Types of testing are; language, scrambled words, arithmetic, codes, spatial relationships, progressive coding. There are several ways of testing and few people score equaly in each. That is because we all have varying aptitudes in different subjects.
Rambling switch is now off.
Cheers