[Indy_Dh]

The fact that a reviewer uses 2 and 4 ratings might not be too meanngful. One reviewer might use 2s and 4s the way another uses 1s and 5s.

There may be reviewers who do not generally fit the bimodal distribution, but if they are the minority, why design your whole rating system around them? Better to optimize your system for the way most of your users behave.

[sfifs]

yes scaled ratings do tend to have subjectivity which in practice we normalize by databasing surveys over time for categories x markets.

The reason online ratings tend to be bimodal is because the respondents are self selecting sample rather than randomized. Since product ratings are not typically compulsory, the extreme likers/dis-likers tend to fill the survey question.

When implemented as compulsory, it drives poor user experience and having to fill a survey to get something anyway introduces a bias (just fill something to get it over with). So no easy answer.

This is also the reason traditional survey firms haven't really gone out of business even with the wealth of online data from Facebook, Twitter and product reviews available, though better/easier access to actual behavioral signals are certainly replacing surveys in some areas.