I am interested in links to scholarly papers with actual comprehensive and preferably up-to-date statistics. I have done some search on Google Scholar but failed to find wide-ranging surveys (the ones I found were either very old (1980) or narrow, dealing with security class action suits (from 2002)).
Although it's difficult to find exact numbers on class action settlements, there are some studies that suggest that the settlements are often of little value to plaintiffs.
A Mayer-Brown paper was only able to obtain data on six settlements - in these cases, claims rates were 0.000006%, 0.33%, 1.5%, 9.66% and 12%.
The same paper found that in one case of an $8 million settlement fund made available to 13,500 members, counsel received $5.5 million.
Appendices A and B of this paper provide further examples where class action settlements are either a negligible amount, or benefited a negligible number of class members.
Although the scope of this paper is somewhat narrow, its findings suggest that it is representative of many class actions.