Ask HN: 1 star ratings with zero feedback in app store

My iPhone app has gotten five 5-star ratings, out of which three have left a review. It has also gotten nine 1-star ratings, out of which none has left a review. So, I have no feedback on what they don't like. Is the app crashing? Is it buggy? Do they think it's useless? Do they want some feature that's missing? My questions for you guys: 1) Is this a common problem with apps, that is, the 1-star raters are much less likely to leave a review than the other raters? 2) Is there anything that can be done to find out some of the reasons behind the 1-star ratings?