Sample Size and Power Determination

Sample Size and Power Determination

taught by Kuber Deokar

Aim of Course:

This online course, "Sample Size and Power Determination" 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 detect a treatment effect of a specified size, if it 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 (such as the significance level and sample size) while others are not (such as unknown parameter values that determine effect magnitudes), 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%?"  This process of finding a balance among factors can be aided by the use of 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 between feasible sample size and acceptable power.

This course may be taken individually (one-off) or as part of a certificate program.
Course Program:

WEEK 1: Introduction to Sample Size Determination and Power,  Including Useful Software

  • Hypothesis tests and confidence intervals
  • Factors that determine sample size
  • Sample size for estimating a population mean
  • Examples, including a study from the literature
  • External and internal pilot studies
  • Ways to estimate sigma
  • What should be avoided:  Retrospective power and standardized effect sizes
  • Ethical issues in power analysis
  • Recommended references
  • Software

WEEK 2: Tests on Population Means (continued)

  • T-Test or Z-Test for population mean?
  • Testing the normality assumption
  • Confidence Intervals on Power and/or Sample Size?
  • Two-sample study from the literature with unequal sample sizes
    • Sample sizes determined by scientist in two stages without software
    • Illustration of more efficient sample determination using software
  • Using coefficient of variation
  • Paired data
  • Additional examples


WEEK 3: Tests on Proportions and Variances

  • One proportion   
    • Software disagreement and rectification
  • Two proportions
  • Options, including transformations built into software, for tests of proportions
  • One variance  and two variances
  • Examples

WEEK 4: Regression and Design

  • Simple linear regression
    • Complexity caused by what must be inputted
  • Multiple linear regression
  • Optional material:  Repeated measures designs, Logrank test for survival analysis
  • Literature references for sample size determination with more advanced
    statistical methods and some information on corresponding software
    capability

HOMEWORK:

Homework in this course consists of short answer questions to test concepts and guided data analysis problems using software.

In addition to assigned readings, this course also has supplemental readings available online.

Sample Size and Power Determination

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.
Level:
Intermediate/Introductory
Prerequisite:
Some familiarity with experimental designs would be helpful, but is not required.  For those working in the life sciences, Biostatistics 1 may also be helpful.
Organization of the Course:
Options for Credit and Recognition:
Course Text:

All necessary materials will be provided online, including a few relevant journal articles.  The Dr. Thomas Ryan's recently published book, Sample Size Determination and Power, is recommended as a reference book.

Software:

Participants should have access to a software package in which they can do power and sample size calculations. Power and Precision, MINITAB, and nQuery are used in the course Notes and examples.  Other software packages such as Stata, PASS, and Russ Lenth’s Java applet may be used for the weekly assignments; assistance with these other packages may be available from the teaching assistants.
Click Here for information on obtaining a free (or nominal cost) copy of software for use during the course.

Instructor(s):

Dates:

November 01, 2019 to November 29, 2019 April 10, 2020 to May 08, 2020 October 30, 2020 to November 27, 2020

Sample Size and Power Determination

Instructor(s):

Dates:
November 01, 2019 to November 29, 2019 April 10, 2020 to May 08, 2020 October 30, 2020 to November 27, 2020

Course Fee: $589

Do you meet course prerequisites? What about book & software? (Click here to learn more)

We have flexible policies to transfer to another course, or withdraw if necessary (modest fee applies)

Group rates: Click here to get information on group rates. 

First time student or academic? Click here for an introductory offer on select courses. Academic affiliation?  You may be eligible for a discount at checkout.

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