Your statistics don't necessarily contradict this survey. Scikit-learn users are a subset of all Python users. Maybe data scientists are more likely to be using

Your statistics don't necessarily contradict this survey. Scikit-learn users are a subset of all Python users. Maybe data scientists are more likely to be using Windows than other Python developers? Its impossible to know from either set of stats. Similarly, stackoverflow has a lot more users than just Python users, so it says little about how many Python programmers use Windows.