In basketball, when one team goes on a scoring run, you will often see the other team call a timeout to try to stop that team's momentum. Has there been any analysis that shows whether calling timeout is actually effective in stopping scoring runs?
According to a preprint article on arXiv titled The causal effect of a timeout at stopping an opposing run in the NBA, the answer is no - in fact:
[W]hile comebacks frequently occur after a run, it is slightly disadvantageous to call a timeout during a run by the opposing team
Another article - a senior thesis, so take that for what it is, though it is mostly a review of other articles - suggests that there is some evidence that teams calling timeout after a "run" of 6-0 will tend to have a better scoring ratio over the short term, but that runs tended to stop whether a timeout was called or not.
It seems likely that timeouts have either a minimal or no effect, given the split in the evidence. This is consistent with other "momentum" related research in various sports, that consistently finds some small difference one way or the other - just like my flipping of a coin consistently finds some small amount of heads or of tails each time I flip it.