Sample Size and Power Determination

Dr. Thomas P. Ryan

Aim of Course:

This course will offer an introduction to sample size and power analysis and will show how to use it simply and effectively to plan the appropriate sample size for a study. The power of a study (the study's ability to prove a treatment effect exists) is determined by such factors as the magnitude of the treatment effect, the sample size, alpha (the level of statistical significance required), and (for survival studies) the study duration.

Since some of these factors are under the researcher's control while others are not, the goal of power analysis is to balance them as a series of "What if's." For example "What sample size would we need if the treatment reduces the risk of death by 10%, and what sample size would we need if the treatment reduces the risk of death by 20%?" Or, "How would power be affected if the study followed patients for two years rather than three?" This process of finding a balance among factors is done most effectively with graphs that allow the researcher to grasp (and communicate) a range of options in a single picture, and find the one that strikes the optimal balance of feasible sample size, reasonable assumptions, and acceptable power. Illustrations include examples from means, proportions, correlations, and survival analysis, and possibly from other procedures as well.

Who Should Take This Course:

Anyone responsible for the planning of a study, or its subsequent analysis. Investigators writing grant applications or other proposals in which sample size must be specified.

For those enrolled in a Program of Advanced Statistical Studies, this is a required or elective course in the following Programs:

• Biostatistics (epidemiology) - required
• Biostatistics (controlled trials) - required
• Statistics for Social Sciences - required
• Statistics for Environmental Science - required

Course Program:

The course is structured as follows

The Instructor:

Dr. Thomas P. Ryan is the author of Modern Engineering Statistics, Modern Experimental Design, Modern Regression Methods and Statistical Methods for Quality Improvement, all from Wiley, plus numerous papers in peer-reviewed journals. He is an elected Fellow of the American Statistical Association, American Society for Quality, and Royal Statistical Society, and has been listed in Marquis Who's Who in America. He served on the Editorial Review Board of the Journal of Quality Technology from 1990 through 2006 and was the Book Review Editor of that journal from 2003 through 2006.

Organization of the Course:

The course takes place over the internet, at statistics.com. During each course week, you participate at times of your own choosing - there are no set times when you must be online. Course participants will be given access to a private discussion board. In class discussions led by the instructor, you can post questions, seek clarification, and interact with your fellow students and the instructor. The course is scheduled to take place over 4 weeks, and typically requires 15 hours per week. At the beginning of each week, you receive the relevant material, in addition to answers to exercises from the previous session. During the week, you are expected to go over the course materials and work through exercises. Discussion among participants is encouraged. The instructor will provide answers and comments.

Certificates and Grades:

You may be interested only in learning the material presented, and not be concerned with grades or certificates. Or you may be enrolled in a statistics.com Program in Advanced Statistical Studies that requires demonstration of proficiency in the subject, in which case your work will be assessed for purposes of issuing a grade. Or you may require only a "Certificate of Course Completion," along with professional development credit in the form of Continuing Education Units (CEU's). As you begin the class, you will be asked to specify your category.

Credit:

This course offers continuing education units (CEU's). For those successfully completing the course (generally this means marks of 50% or better on the homework), 5.0 CEU's and a certificate will be issued by statistics.com, upon request.

Dates:

Nov. 27 - Dec. 30, 2009
May. 14 - Jun. 11, 2010
Click here to be notified of future course offerings.

Participants gain access to the online materials on the first day of the course, and typically spend about 15 hours per week (at their convenience). You retain full access to course materials, including discussion board, for two weeks after the course closing date.

Level:

Intermediate/Introductory

Prerequisite:

Participants should be familiar with basic statistics (such as the background provided by Basic Concepts in Probability and Statistics, Introduction to Statistics 1: Inference for a Single Variable, and Introduction to Statistics 2: Working with Bivariate Data). For those working in the life sciences, Introduction to Biostatistics may also be helpful. For additional information about course prerequisites,For additional information about course prerequisites, click here.

Course Text:

All necessary materials will be provided online. The user guide to Power and Precision will also be used; this is available to anyone who uses the evaluation version of the program.

Software:

Participants should have access to a software package in which they can do power and sample size calculations. The instructor will provide examples and/or feedback using Power and Precision. Click Here for information on obtaining a free (or nominal cost) copy of this package for use during the course.

Registration:

Register Online - $469
Register Online (academic) - $369 (you must be affiliated with a college, university or high school)

Add $50 service fee if you require a prior invoice, or if you need to submit a purchase order or voucher, pay by wire transfer or EFT, or refund and reprocess a prior payment. Please use this printed registration form, for these and other special orders.

Note: Courses may fill up at any time and registrations are processed in the order in which they are received. Your registration will be confirmed for the first available course date, unless you specify otherwise.

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