[nabla9]

Crude estimate based on some self evident truths:

Logarithms for number of people and communication chain come from network theory because network size and network distances slow down information flow.

New technologies bring in unexpected delays and problems that rapidly accumulate in nonlinear ways. If bring in 20 people to work with new programming language, new library stack, etc. everything slows down to crawl.

[8organicbits]

From the other angle, you can see how velocity is impacted by using "boring tech", keeping teams small (two pizza team), clearly identifying stakeholder roles, creating efficient communication channels. It's a pretty useful model.