Whether or not accelerators increase the success of accelerated firms is stillnot aalways subject of discussionclear. A number of studies have shown that accelerated cohorts perform better than non-accelerated firms, but this is potentially due to the selection effect of programmes. However, studies using [[regression discontinuity design]] show that accelerators can indeed have impact over and above their selection effect, and may also have wider ecosystem spillovers (although this does not necessarily apply to every program).<ref>{{Cite report |authors= Jonathan Bone, Juanita Gonzalez-Uribe, Christopher Haley, Henry Lahr |date=2019 |title=THE IMPACT OF BUSINESS ACCELERATORS AND INCUBATORS IN THE UK |url=https://www.gov.uk/government/publications/the-impact-of-business-accelerators-and-incubators-in-the-uk |publisher=BEIS}}</ref>
