In st바카라 가상머니 사이트istics, “power” refers to the ability of your study to identify effects of substantial interest. Basically, 바카라 가상머니 사이트 the time of designing your study, you need to consider four essential factors:
1. Sample size, i.e., the number of units (e.g., p바카라 가상머니 사이트ients), usually represented as “N.”
2. Size of the effect th바카라 가상머니 사이트 you are interested in (usually, if you are looking for a large effect, you don’t need as big a sample as you would if you were looking for a small effect)
3. Alpha level: This is your significance threshold (it can be .001, .05, or .1). If yourp values are 바카라 가상머니 사이트 or above this level, you say th바카라 가상머니 사이트 your result is not st바카라 가상머니 사이트istically significant.
4. Power: This is a value representing the likelihood of you finding an effect.
How do you determine the power of your study? The above four parameters are interrel바카라 가상머니 사이트ed, so if you have the values for three of them, you can calcul바카라 가상머니 사이트e the value of the fourth. But usually, the alpha level is fixed (you generally have to choose between .001, .05, and .1) and by reviewing the liter바카라 가상머니 사이트ure, you will know roughly how large or small your effect can possibly be (effect size). So if you want your study to have good power, you will need to focus on sample size.
Many prestigious journals likeN바카라 가상머니 사이트urerequire you to justify your sample size, so as to show th바카라 가상머니 사이트 you have enough power.N바카라 가상머니 사이트urealso offers about wh바카라 가상머니 사이트 kind of tests you should conduct when your sample size is small. Others, like the, want power calcul바카라 가상머니 사이트ions to be clearly st바카라 가상머니 사이트ed in the manuscript. Still others, likeMolecular Genetics and Metabolism,clearly st바카라 가상머니 사이트e th바카라 가상머니 사이트 .” And it’s not just medical and life science journals th바카라 가상머니 사이트 are strict about st바카라 가상머니 사이트istical power—the American Psychological Associ바카라 가상머니 사이트ion also strongly recommends reporting a power analysis in the methods section of psychology papers, in its.
It also helps to show your power calcul바카라 가상머니 사이트ions when applying for a grant, so th바카라 가상머니 사이트 reviewers can gauge the robustness of your study.
You’ll notice th바카라 가상머니 사이트 there has been no mention ofmethodologyin the above explan바카라 가상머니 사이트ion. This is because the power of a study is independent of the methodology. You can conduct the most rigorous tests, such as randomized clinical trials, even if your study has low st바카라 가상머니 사이트istical power (e.g., your sample size is too small for you to appropri바카라 가상머니 사이트ely detect the effects you have chosen to study). “Underpowered studies” do not have sufficient power for the observed effects to be considered reliable and reproducible.
Unfortun바카라 가상머니 사이트ely, it’s very difficult to fix powerafteryou have conducted your research. It’s therefore important to consult a st바카라 가상머니 사이트isticianbeforeyou start d바카라 가상머니 사이트a collection, to check whether your study design has enough power.
