Home About Calendar Cart

Online Workshops

Calculating Power and Sample Size

Overview:

Learn the theory, the logic, and the steps to calculate power and sample sizes so you can easily get started on your research project.

Every granting agency and many committees require sample size and power estimates before funding a study.

But most statistics classes don't teach you how to calculate them. Sure, maybe for one-sample t-tests, if anything, but not for the real kinds of statistics you need to actually use.

Mainstream statistical software makes it easy to calculate power after the fact, which is dubious, at best, and prone to misinterpretation.

This 3-hour workshop will get you up to speed on the meaning and logic of power, sample size, and how to calculate them. We'll start with a review, from the beginning, of what power means and how it relates to the statistical tests, effect sizes, standard deviations, and sample size.

You will learn how to calculate simple sample estimates using two types of specialized software (one free and one commercial).

 
Format:

We've designed the format to support your learning and convenience:

Web based online workshop. You'll get:

1. Training Materials

  • 3 hours of training videos to download and watch on your own time (and keep forever). The videos are screen shots of what is happening on my computer screen. They include both presentations as I go over the concepts and software demonstrations.

  • pdf handouts of the presentation slides for note-taking

  • exercises to practice what you've learned, with answers to check your work.

  • written, searchable pdf enhanced transcripts of all videos. We call these enhanced transcripts, because not only do we have them transcribed by a real person and edit them extensively to make them easier to read, on each page we import the presentation slides and screenshots so you can see all the relevant graphs and equations as you're reading.

  • recommended resources and references to cement and expand your learning.

2. Two Live Q&A Webinars

After you've had a few days to work through all the training materials, we'll meet in a live Question & Answer webinar. They're scheduled on two different days, one in the daytime and one in the evening, to meet the needs of any time zone and work schedule.

You attend over the internet. Audio is through either your computer speakers/microphone or by telephone. Ask questions out loud or write it into the chat.  You'll be able to see my screen, so I can show you how to do something in SPSS, draw you a graph, or we can review the output.

I highly encourage you to attend the Q&A Sessions live, but if you have to miss one (it happens) they will be recorded and made available within 24 hours on our workshop website. You can still get your questions answered by submitting a question before a Q&A and I'll cover it in the session.

3. Private workshop website

This is where you can submit questions and get all the workshop materials.

This private website contains everything you need: Workshop materials to download, bonus videos, the exercises, Q&A information and recordings, a contact form to get some help if you get stuck with anything.

But best of all, you can submit questions. So if something isn't clear while you're watching the training, pause your video and type in your question. We'll answer quick questions right there on the website, and things that are more in-depth, we'll cover in the next Q&A.

It's all the advantages of a live workshop without the disadvantages.

You don't have to drop a few thousand travelling to a workshop and take a few days off work. And best of all, because you’re not travelling, we don’t have to concentrate an overwhelming amount of information into a marathon session. We can spread it out in digestible amounts.

So you really learn it. Inside out.

And best of all, unlike live workshops, you keep the workshop recordings forever. So if you need to review the material in a few months, or years, or find yourself needing to run a new type of model, you can watch it again.
What You Will Learn:

 
You will learn:
  • A review of power, effect sizes, hypothesis tests, and Type I and Type II errors, explained so you get an intuitive understanding

  • How power, effect size, and standard deviation relate to sample size in a variety of statistical tests--including t-test, ANOVAs, linear and logistic regressions

  • The logic of sample size calculations, so you can apply it to any problem

  • The five pieces of information you need to do any sample size calculation, where to get them, and the steps for implementing them

  • Your options for increasing power in a study

  • The importance of effect sizes to power and sample size calcuations and the best way to measure them in a variety of tests

  • Why it really isn't useful to do power calculations after running a study

  • Where sample size calculations fit into the eleven steps of data analysis

  • How to do simple sample size calculations using a free online calculator

  • How to do more complex calculations using StudySize 2.0 Software and G*Power

  • Examples of prospective sample size estimates for a two sample t-test, and ANOVA, a multiple regression, and a logistic regression analysis in all three software packages
Who Is It For:
This workshop is for you if you:
  • Need to calculate sample size estimates for grant proposals, dissertation proposals, or just want to be able to make sure a research study is worth doing.

  • Will be writing a dissertation proposal this semester

  • Learned the basics of power and sample size in statistics class, but never really how to do them in real research situations or in anything harder than a t-test

  • Have a statistical consultant available to help you calculate sample sizes, but need to understand what pieces of information to hand over to her or him and how to get that information.

Prerequisites:

  • You will get the most out of the workshop if you have had at least two statistics classes and experience in data analysis.

You do not need experience in any specific statistical software. We will be using three software--a free online java applet, G*Power, and StudySize 2.0. G*Power is available free. You can get a free 3-week trial download of StudySize 2.0, which I recommend you do just before the workshop. I will send instructions at the time.
What's Included:
  • Training videos. This module is approximately 3 hours of training.

  • Two 60-minute Webinar Q&A sessions. Just your questions and my answers. They will be scheduled a few days after the training materials are released so you have time to watch the videos, do the exercises, and even try things out on your own data. Then come back with questions. It's when you use these techniques on your own data that you cement your learning.

  • Access to our private workshop web site. We’ve created a membership site that you become a member of.  For a year. 

    Submit questions, get call-in information for Q&A sessions, ask for customer support, and download handouts, recordings, and bonus materials. Then come back after the workshop is over and watch the videos again and ask questions as they come up for you – for a whole year.
  • PDF handouts of the presentation, which will be available ahead of time, on which you can take notes.

  • Access to our private workshop web site. We’ve created a membership site that you become a member of.  For a year.  Submit questions, get call-in information for Q&A sessions, ask for customer support, and download handouts, recordings, and bonus materials. Then come back after the workshop is over and watch the videos again and ask questions as they come up for you – for a whole year.

  • written, searchable pdf enhanced transcripts of all videos. We call these enhanced transcripts, because not only do we have them transcribed by a real person and edit them extensively to make them easier to read, on each page we import the presentation slides and screenshots so you can see all the relevant graphs and equations as you're reading.

  • recommended resources and references to cement and expand your learning.

  • You are encouraged to ask questions about calculating your own sample size estimates in addition to general questions about the topic.  (But please keep questions to the topic of the workshop so that they’re useful for everyone). 

  • Exercises and answers.  (Yes, homework!).  You’ll get more out of the workshop if you participate fully by doing homework.  We suggest you use one of the data sets provided, so you can check answers, then redo them on your own. It's when you do statistics on your own data that it really starts to make sense.

Have a question about whether you're doing it right on your own data? Bring it to the Q&A session.
The Instructor:

Karen Grace-Martin, the workshop instructor and founder of The Analysis Factor, is a professional statistical consultant with masters degrees in both applied statistics and social psychology.  Her own career started in psychology research, where her frustration in applying statistics to her data led her to learn more statistics. 

Karen was a professional statistical consultant at Cornell University for seven years before founding The Analysis Factor.  She has guided and trained researchers through their statistical analysis for over 15 years. Her focus is on helping statistics practitioners gain an intuitive understanding of how statistics is applied to real data in research studies.
Dates & Times:

The workshop training materials will be released on:

  • Tuesday, August 30

The live Question & Answer sessions will be held:

  • Thursday, September 1 at 8pm EST (GMT-5)  
  • Friday, September 2 at 12pm (noon) EST (GMT-5)  

 
Registration:

This workshop has ended. If you'd like a notice when the next session is scheduled, please fill in your name and email address below.

Name
Email

 
Free Bonuses

Everyone will receive two free bonus recordings:

1. A 60 minute Audio Presentation: The 11 Steps to Performing Any Statistical Model

All statistical modeling--whether ANOVA, Multiple Regression, Poisson Regression, Multilevel Model--is about understanding the relationship between independent and dependent variables. The content differs, but as a data analyst, you need to follow the same 11 steps to complete your modeling.

This audio will give you an overview of these 11 steps:

  • what they are
  • why each one is important
  • the general order in which to do them
  • on which steps the different types of modeling differ and where they're the same

Understanding the steps will make your modeling more efficient and keep you on track.

2. A 60-minute Video Presentation: The First 3 Steps to Statistical Modeling: How to Clarify the Research Question, the Design, and the Variables

All statistical modeling--whether ANOVA, Multiple Regression, Poisson Regression, Multilevel Model--is about understanding the relationship between independent and dependent variables. The first 3 steps in modeling set up the entire rest of the analysis.

1. Write out research questions in theoretical and operational terms

2. Design the study or define the design

3. Choose the variables for answering research questions and determine their level of measurement

It is the way you do these three steps that determines the rest of the analysis. Doing them explicitly and doing them well can save you days of time and endless frustration.

 
Refund Policy

Your registration fee is fully refundable up to 72 hours in advance minus a $15 administration fee. Because enrollment is limited, no refunds will be granted after the program begins.

That said, your satisfaction is guaranteed. If you participate in the full workshop and find you are not satisfied for any reason, we will give you a full refund. Just notify us within 90 days of the conclusion of the program.