Butt it is still not clear to what extent this might be due to 'selection bias' - cancer patients over-reporting mobile phone use on the side of the head where their tumour arose.
There was still more cheating than in the control group, but simply by bringing attention to the fact that over-reporting answers was, in fact, cheating, the total amount of cheating was reduced.
仅仅通过使人们意识到过度报告自己测验中正确的回答数，事实上就是作弊时，作弊的数量反而降低了。
3
The messaging systems have changed over time; as such reporting standards and message format have changed as well.