# Confused when to use Population vs Sample standard deviation in engineering testing

When I run an test for something (say 10 trials) and want to find the standard deviation of all 10 trials, I am getting confused if I should use the sample or population standard deviation. My initial thought would be the sample standard deviation since I could run 10 more trials and now have more data points thus never having the complete population.

A lot of the examples I see online involve student grades or finance applications (which I never deal with) but I am having trouble finding a concrete answer on what to do when it is possible to run more tests and have more data points but using all the data points you have to get a standard deviation.

For any given set of numbers the sample standard deviation is larger than the population standard deviation because there is extra uncertainty involved: the uncertainty that results from sampling. See this for a bit more information: Intuitive explanation for dividing by $n-1$ when calculating standard deviation?