What is "power cut"? I am reading Yudi Pawitan's In All Likelihood chapter 7 section 5. He mentioned the following in sequential design using likelihood approach with justification of stopping rule not affecting likelihood inference.
'A strict adherence to the strong likelihood
principle in this case implies that the evidence from such an experiment
does not depend on the stopping rule. That is, if we want to find out
what the data say, we can ignore the stopping rule in the analysis. This is
convenient if we stop a study for some unrelated reason (e.g. a power cut),
but it is also the case even if we decide to stop because ‘we are ahead’ or
the ‘data look good’.'
Q1: What is power cut here? Is it just lowering originally planned 80% power to 50% by early stopping?
Q2: When do we use power cut? Most of studies will not be overpowered as it is a waste of resources to overpower.

This is an interesting observation: the paragraph talks about experiments and how to analyze them if stopped early. So it's not a stretch to connect "power cut" with "statistical power", a concept relevant to planning scientific experiments. However, In All Likelihood takes an informal approach*, so the odds are (pun intended) that "power" refers to electricity and "power cut" means a power outage.
٭ From the description on Goodreads: "The book generally takes an informal approach, where most important results are established using heuristic arguments and motivated with realistic examples."
