What does it mean to have adequate power to conduct a study?

1. adequate power is enough certainty, with good probability, that you do not have a Type I or Type II error
2. 2. adequate power is estimating the magnitude of the true effects of the variable in the population
3. Having enough participants to be able to conduct the study legitimately

Sarah is planning her dissertation and she wants to study highly religious teenage girls with eating disorders. She doesn't have a large ready-made sample of people she can obtain for her study. She has a sample size of 40. Knowing estimating adequate power, which one Sarah should NOT do.

1. study a hypothesis that lends to have a large effect in previous research
2. Consider adjusting alpha value (not p=.05) but mention in the proposal and be honest
3. keep the number of variable in the study as small as possible
4. Increase the number of variables in the study