Statistical power must be determined before an experiment to establish the sample size needed to detect an expected difference between groups.

“the only way you can say it's not significant is you have to know what it was powered to detect um and statistical power is a very important concept that probably doesn't get discussed enough but before you do an experiment you have to have an expectation of what you believe the difference is between the groups and you have to determine the number of samples you will need to assess whether or not that difference is there or not so you use something it's called a power table”