• Skip to primary navigation
  • Skip to main content
  • Skip to primary sidebar
The Analysis Factor

The Analysis Factor

Statistical Consulting, Resources, and Statistics Workshops for Researchers

  • our programs
    • Membership
    • Online Workshops
    • Free Webinars
    • Consulting Services
  • statistical resources
  • blog
  • about
    • Our Team
    • Our Core Values
    • Our Privacy Policy
    • Employment
    • Collaborate with Us
  • contact
  • login

Sample Size Calculations

Three Issues in Sample Size Estimates for Multilevel Models

by Karen Grace-Martin  4 Comments

If you’ve ever worked with multilevel models, you know that they are an extension of linear models. For a researcher learning them, this is both good and bad news.

The good side is that many of the concepts, calculations, and results are familiar. The down side of the extension is that everything is more complicated in multilevel models.

This includes power and sample size calculations. [Read more…] about Three Issues in Sample Size Estimates for Multilevel Models

Tagged With: Intraclass Correlation Coefficient, multilevel model, Sample Size Calculations

Related Posts

  • Sample Size Estimates for Multilevel Randomized Trials
  • Multilevel, Hierarchical, and Mixed Models–Questions about Terminology
  • Covariance Matrices, Covariance Structures, and Bears, Oh My!
  • Concepts in Linear Regression you need to know before learning Multilevel Models

Sample Size Estimates for Multilevel Randomized Trials

by Karen Grace-Martin  2 Comments

If you learned much about calculating power or sample sizes in your statistics classes, chances are, it was on something very, very simple, like a z-test.

But there are many design issues that affect power in a study that go way beyond a z-test.  Like:

  • repeated measures
  • clustering of individuals
  • blocking
  • including covariates in a model

Regular sample size software can accommodate some of these issues, but not all.  And there is just something wonderful about finding a tool that does just what you need it to.

Especially when it’s free.

Enter Optimal Design Plus Empirical Evidence software. [Read more…] about Sample Size Estimates for Multilevel Randomized Trials

Tagged With: multilevel model, Optimal Design, Power Analysis, Randomized Trials, Sample Size Calculations

Related Posts

  • Three Issues in Sample Size Estimates for Multilevel Models
  • Multilevel, Hierarchical, and Mixed Models–Questions about Terminology
  • Member Training: Power Analysis and Sample Size Determination Using Simulation
  • Covariance Matrices, Covariance Structures, and Bears, Oh My!

5 Reasons to Run Sample Size Calculations Before Collecting Data

by Karen Grace-Martin  6 Comments

Most of us run sample size calculations when a granting agency or committee requires it.  That’s reason 1.

That is a very good reason.  But there are others, and it can be helpful to keep these in mind when you’re tempted to skip this step or are grumbling through the calculations you’re required to do.

It’s easy to base your sample size on what is customary in your field (“I’ll use 20 subjects per condition”) or to just use the number of subjects in a similar study (“They used 150, so I will too”).

Sometimes you can get away with doing that.

However, there really are some good reasons beyond funding to do some sample size estimates. And since they’re not especially time-consuming, it’s worth doing them. [Read more…] about 5 Reasons to Run Sample Size Calculations Before Collecting Data

Tagged With: Calculating Sample Size, Sample Size Calculations, Statistical power

Related Posts

  • 5 Steps for Calculating Sample Size
  • How the Population Distribution Influences the Confidence Interval
  • How Confident Are You About Confidence Intervals?
  • How to Interpret the Width of a Confidence Interval

Primary Sidebar

This Month’s Statistically Speaking Live Training

  • Member Training: Moderated Mediation, Not Mediated Moderation

Upcoming Workshops

    No Events

Upcoming Free Webinars

TBA

Quick links

Our Programs Statistical Resources Blog/News About Contact Log in

Contact

Upcoming

Free Webinars Membership Trainings Workshops

Privacy Policy

Search

Copyright © 2008–2023 The Analysis Factor, LLC.
All rights reserved.

The Analysis Factor uses cookies to ensure that we give you the best experience of our website. If you continue we assume that you consent to receive cookies on all websites from The Analysis Factor.
Continue Privacy Policy
Privacy & Cookies Policy

Privacy Overview

This website uses cookies to improve your experience while you navigate through the website. Out of these, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website. We also use third-party cookies that help us analyze and understand how you use this website. These cookies will be stored in your browser only with your consent. You also have the option to opt-out of these cookies. But opting out of some of these cookies may affect your browsing experience.
Necessary
Always Enabled
Necessary cookies are absolutely essential for the website to function properly. This category only includes cookies that ensures basic functionalities and security features of the website. These cookies do not store any personal information.
Non-necessary
Any cookies that may not be particularly necessary for the website to function and is used specifically to collect user personal data via analytics, ads, other embedded contents are termed as non-necessary cookies. It is mandatory to procure user consent prior to running these cookies on your website.
SAVE & ACCEPT