In this note, we discuss the use of Cohen’s D for planning difference-of-mean experiments.
Estimating sample size
Let’s imagine you are testing a new weight loss program and comparing it so some existing weight loss regimen. You want to run an experiment to determine if the new program is more effective than the old one. You’ll put a control group on the old plan, and a treatment group on the new plan, and after three months, you’ll measure how much weight the subjects lost, and see which plan does better on average.
Nina and I have been sending out drafts of our book Practical Data Science with R 2nd Edition for technical review. A few of the reviews came back from reviewers that described themselves with variations of:
Senior Business Analyst for COMPANYNAME. I have been involved in presenting graphs of data for many years.
To us this reads as somebody with deep experience, confidence, and bit of humility. They do something technical and valuable, but because they understand it they do not consider it to be arcane magic.
In this note we describe might can happen if such a person (or if a junior version of such a person) acquires 1 or 2 technical books.