# How to choose a Power and Alpha combination for a fixed sample size?

Let's say I have a sample size established with alpha=0.05 and power=0.8 (based on time constraint for study).

The same sample size can be achieved with any of:

alpha = 0.001 and power = 0.31
alpha = 0.01 and power = 0.58
alpha = 0.25 and power = 0.95
alpha = 0.999 and power = 0.998


I want to know is what levels of risk to expect from the study of this size: what alpha I can aim for and what power I can hope to achieve.

Which combination of alpha and power do I adopt? Why?