OverviewTeaching: 60 min Exercises: 120 minQuestions
What is power
Why is it important: issues with low statistical power
Some tools for power for neuroimagingObjectives
After this lesson, you should understand what is Power, and the issues of low statistical power
First, we will be doing some work on this notebook:
How to work with the notebook ? There are two cases.
Exercise: visit this site and set your test to be one tailed at the false positive risk of 0.05. Say a typical effect size in fMRI corresponds to a Cohen’s d of 0.5. What is the sample size that you find ? Now, relate to what we are doing in fMRI. What is the problem ? can you use this online tool to get the number of subjects for your experiment ? if yes, give a typical example, if not, explain the problem.
Then, on this one:
Last, you’ll need to go through :
The lack of power is much more problematic that it seems at first sight. - It would usually lead to wasted resources - If an under powered study yields some significant effects, these are likely to be overestimated - If an under powered study yields some significant effects, these are less likely to replicate