## An Introduction to Basic Statistics for Biologists using R – Session Four

This is Session Four of our free on-demand online course based around the book An Introduction to Basic Statistics for Biologists using R, and it assumes that you have a copy of this workbook in front of you so you can follow the instructions for each exercise provided in it. To find out where to purchase this book, click here. If you would prefer to complete a more detailed distance-learning or in-person version of the course that includes a certificate of attendance and completion and is led by one of the authors of An Introduction to Basic Statistics for Biologists using R, click here to find out when the next one is scheduled.

The information on this page will take you through the exercises in Chapter Six of the above book. These exercises cover how to compare data from different groups using a variety of statistical tests in R. You can find the introduction and the links to other sessions in this course here.

### Using Statistical Analysis to Compare Data from Different Groups in R

Overview: In this session, you will learn how to compare data from different groups in order to determine whether there is a significant difference between them. This includes using tests to compare the central values (means or medians) of two groups, tests to compare the central values of paired groups, tests to compare the variance between groups, tests to compare three or more groups and tests to compare frequency of occurrence data. Duration:. This session will take approximately three hours to complete.

#### Part One – Introductory Video

This video provides a summary of the introductory information for this chapter which you will find on pages 127 and 128 of An Introduction to Basic Statistics for Biologists using R. If you cannot see the video in the space below, click here to open a pop-out video viewer for it. Running Time: 3 minutes 30 seconds.

#### Part Two – Getting Started

This video outlines what you need to do to get ready to start the exercises in this chapter. The instructions for doing this can be found on pages 128 to 130 of An Introduction to Basic Statistics for Biologists using R. If you cannot see the video in the space below, click here to open a pop-out video viewer for it. Running Time: 1 minute 4 seconds.

#### Part Three – Exercise 4.1: How to Test for Differences in the Central Values (Means/Medians) of Two Groups

This video introduces Exercise 4.1, including the tests that you can use to compare central values of two groups, and the structure that your data need to have in order to be able to do this in R. This information can also be found on page 130 of An Introduction to Basic Statistics for Biologists using R. If you cannot see the video in the space below, click here to open a pop-out video viewer for it. Running Time: 2 minutes 42 seconds.

Once you have watched this video, you can work through the instructions for this exercise which you will find on pages 131 to 144 of An Introduction to Basic Statistics for Biologists using R. These will provide you with all the information you need to successfully complete it.

#### Part Four – Exercise 4.2: How to Test for a Difference in the Central Values (Means/Medians) of Two Paired Groups

This video introduces Exercise 4.2, including the tests that you can use to compare central values of two paired groups, and the structure that your data need to have in order to be able to do this in R. This information can also be found on pages 144 and 145 of An Introduction to Basic Statistics for Biologists using R. If you cannot see the video in the space below, click here to open a pop-out video viewer for it. Running Time: 3 minutes 24 seconds.

Once you have watched this video, you can work through the instructions for this exercise which you will find on pages 145 to 154 of An Introduction to Basic Statistics for Biologists using R. These will provide you with all the information you need to successfully complete it.

#### Part Five – Exercise 4.3: How to Test for a Difference in the Variances of Two or More Groups

This video introduces Exercise 4.3, including what variance is, what tests you can use to compare the variances of two or more groups, and the structure that your data need to have in order to be able to do this in R. This information can also be found on pages 154 and 155 of An Introduction to Basic Statistics for Biologists using R. If you cannot see the video in the space below, click here to open a pop-out video viewer for it. Running Time: 3 minutes 35 seconds.

Once you have watched this video, you can work through the instructions for this exercise which you will find on pages 156 to166 of An Introduction to Basic Statistics for Biologists using R. These will provide you with all the information you need to successfully complete it.

#### Part Six – Exercise 4.4: How to Test for Differences Between Three or More Groups

This video introduces Exercise 4.4, including why you need specific tests to compare data from three or more groups, what tests you can use to do this, and the structure that your data need to have in order to be able to do this in R. This information can also be found on pages 167 and 168 of An Introduction to Basic Statistics for Biologists using R. If you cannot see the video in the space below, click here to open a pop-out video viewer for it. Running Time: 3 minutes 54 seconds.

Once you have watched this video, you can work through the instructions for this exercise which you will find on pages 169 to 177 of An Introduction to Basic Statistics for Biologists using R. These will provide you with all the information you need to successfully complete it.

#### Part Seven – Exercise 4.5: How to Test for Differences in Frequencies of Occurrence Measured on an Ordinal or Categorical Scale

This video introduces Exercise 4.5, including what frequency data are, what tests can be used to compare them, and how your data need to be structured in order to be able to do this in R. This information can also be found on pages 177 and 178 of An Introduction to Basic Statistics for Biologists using R. If you cannot see the video in the space below, click here to open a pop-out video viewer for it. Running Time: 4 minutes 56 seconds.

Once you have watched this video, you can work through the instructions for this exercise which you will find on pages 179 to 189 of An Introduction to Basic Statistics for Biologists using R. These will provide you with all the information you need to successfully complete it.

#### End of Session Four

Once you have worked through the five exercises in this session, you can click here to move on to the fifth and final session (based on Chapter Seven of An Introduction to Basic Statistics for Biologists using R) or you can click here return to the home page for this course.