Further to Vidiot and DJS, I have wondered myself in the past whether the issue is whether low education is due to the cult or vica versa. IMO a desire for educational achievement is at least partially cultural, and the JW culture in relation to education is about as negative as it can get. However, I sense that the cult is a bit of a haven for those who want to hide. So my 2c worth: I think it is a bit of both.
Back to the original topic, here is a table I extracted from the 2011 census in relation to how JW's fare against other Australians in terms of education:
This is raw data I extracted directly from the ABS database a while ago. It doesn't compare JW's against other religions, but shows they are pretty poor on the academic front, compared to the average.
I will make some other posts in relation to Aust census data. I have a fair bit of info, but not in easily presentable form.