Competition and welfare - empirical evidence Consider the following claims:


less competitive markets deliver worse outcomes for consumers,
less competitive markets deliver lower social welfare,
less competitive markets deliver higher prices/lower quality.


These might be considered fairly canonical claims in the sense that they emerge naturally from many 'textbook' models from introductory economics or industrial organization. That means that many students of economics are exposed to such claims through the lens of theory. I would like to supplement this with empirical evidence.

I am looking for references to empirical work that supports or refutes one or more of the abovee claims (or close variants of them). Particularly welcome would be survey articles covering literatures that address them.
Here is a fact sheet by the OECD about the effects of competition. It is mostly concerned with growth and productivity, but also discusses the effects on poor consumers and prices. It cites a wide range of empirical studies that you might find of interest. 

https://www.oecd.org/daf/competition/2014-competition-factsheet-for-print-en.pdf

OECD, Factsheet on how competition policy affects macro-economic outcomes, 2014.