There’s plenty of research on reliability of rating scales—and the sweet spot seems to be a range from 7-10 choices at least according to quite a few studies designed to address this directly. An influential paper in this regard is Preston & Coleman’s (2000) “Optimal number of response categories in rating scales: reliability, validity, discriminating power, and respondent preferences.” link to PDF
Abstract:
Using a self-administered questionnaire, 149 respondents rated service elements associated with a recently visited store or restaurant on scales that differed only in the number of response categories (ranging from 2 to 11) and on a 101-point scale presented in a different format. On several indices of reliability, validity, and discriminating power, the two-point, three-point, and four-point scales performed relatively poorly, and indices were significantly higher for scales with more response categories, up to about 7. Internal consistency did not differ significantly between scales, but test-retest reliability tended to decrease for scales with more than 10 response categories. Respondent preferences were highest for the 10-point scale, closely followed by the seven-point and nine-point scales.
Or if one prefers a more analytic approach, here’s a 2012 conference proceedings paper by Kluver et al “How many bits per rating?” link to PDF
There’s plenty of research on reliability of rating scales—and the sweet spot seems to be a range from 7-10 choices at least according to quite a few studies designed to address this directly. An influential paper in this regard is Preston & Coleman’s (2000) “Optimal number of response categories in rating scales: reliability, validity, discriminating power, and respondent preferences.” link to PDF
Abstract:
Or if one prefers a more analytic approach, here’s a 2012 conference proceedings paper by Kluver et al “How many bits per rating?” link to PDF