Not specific to scrum but I am reminded of a part from Peopleware:
"The most surprising part of the 1985 Jeffery-Lawrence study appeared at the very end, when they investigated the productivity of 24 projects for which no estimates were prepared at all. These projects far outperformed all the others (see Table 5-3)."
Table 5-3 Productivity by Estimation Approach (Full Result)
-----------------------------------------------------------------------
Effort Estimate Prepared by Average Productivity Number of Projects
-----------------------------------------------------------------------
Programmer alone 8.0 19
Supervisor alone 6.6 23
Promgrammer & supervisor 7.8 16
System analyst 9.5 21
(no estimate) 12.0 24
Not scrum-specific, and I don't recall whether it was backed by academic research, but one of the rules in XP is that estimates longer than 3 weeks were (more) unreliable. So if the estimate was longer than 3 weeks, you had to break it up into chunks, each of which was 3 weeks or smaller.
"The most surprising part of the 1985 Jeffery-Lawrence study appeared at the very end, when they investigated the productivity of 24 projects for which no estimates were prepared at all. These projects far outperformed all the others (see Table 5-3)."
Source: https://www.amazon.com/Peopleware-Productive-Projects-Teams-...