Dear Professor Mean,
For several years now, I have enjoyed reading your webpage and have recently purchased your text- thank for your efforts in helping those of us attempting to learn biostatistics. I’ve been struggling with a design/analysis question related to repeated measures design and power analysis. I’m not sure if you are currently accepting questions of this nature, and thought I would check to see if this would be OK. I certainly understand if this is something that you would rather not involve yourself with.
Loyal Reader
Dear Reader,
I do appreciate the compliments. I’m starting a new career as an independent statistical consultant, so I am certainly glad to answer questions for anyone who has funds available.
Most of the people who write to me, though, do not have a lot of cash at hand that they can give to a consultant. I’ve always had the policy of providing quick answers if at all possible. For many questions, I can do this in 15 minutes or less. It’s not going to be the optimal response because of time constraints and because email is not a good way to answer complex questions. Any advice I give should not be taken as a substitute for a face-to-face consultation with a professional statistician. Still, a quick answer can sometimes be of great help to someone.
I get some benefits from this also, as I will usually create webpage with your question and my response. This helps advertise my services and show the types of questions I can answer.
I’m very careful to try to preserve individual privacy, but if I fail to do this properly, just let me know and I will modify or remove the offending webpage.
I only have a limited amount of time and sometimes I have a huge backlog of unanswered questions. If you need a fast response, you can try writing to me again, but since I am doing this for free, please don’t expect me to drop everything for your particular question.
Sometimes a question gets lost in the shuffle and I do apologize if you ask a question and never get a response. My goal is to provide at least a short response to anyone who writes in, though it may be a response like “Sorry but I can’t help with this type of question”. If you think your question has gotten lost, don’t be afraid to ask again.
In all my years of answering questions, I have only had one person respond rudely to my answer and when I explained how busy I was, they apologized. Given how nasty many email exchanges on the Internet can be, I consider myself very fortunate.
By the way, for this particular question, I sent back a brief email asking for more details. I also offered some very general comments, which you can read at
P.Mean: Power calculations for repeated measures designs. Created 2008-09-25.
2008-10-26 update: Someone else asked a question for something that was obviously a homework question for a basic statistics class. I generally encourage people who have homework questions to discuss it with their teacher rather than with me. There are several practical reasons for this.
Every teacher has a slightly different approach and I am not capable of discerning what these individual differences would be.
- I don’t want to antagonize your teacher by providing more help that your teacher might want you to have.
- I only have a limited amount of time in the day. I’d rather help those people who don’t have a teacher that they can go to for help.
In spite of this, I will usually offer some general advice, but not specific answers, to homework questions.