DALBAR's work is mentioned every once in a while here and this article raises questions about both their calculations and conclusions along with those of M*. While the headline and first paragraph below claim that investors do not underperform their investments, my sense, possibly incorrect, is that the article is actually only saying DALBAR's and M*'s calculations don't support the conclusions they're drawing without suggesting the actual result would be the opposite. In any event I found it an interesting read and an open question as to what should be done about it if the author is correct.
"For 23 years DALBAR, Inc. has been publishing a research report reaching the conclusion, year after year, that investors underperform the investment vehicles that they invest in due to “poor investor decision making.” Wade Pfau recently discovered, however, that this conclusion is the result of a serious calculation error. Now, using Pfau’s results, I will prove that the evidence actually shows that investors do not underperform their investments."
https://advisorperspectives.com/articles/2017/10/09/investors-do-not-underperform-their-investments
