Scientists often plan for studies by calculating how many subjects or units need to be tested in order to find an effect. That is, they plan for a study using statistical power according to principles of hypothesis testing. Sample size calculations are usually required in ethics applications and grant proposals to justify the study. We previously learned how to calculate
Read more
Various tools, scales and techniques are available to researchers to quantify outcome measures. Some of these tools are familiar, like a weight scale to measure weight loss over the course of an exercise program. Others are less familiar and are only understood by those working in the same field. Furthermore, different outcome measures can be calculated from the same data.
Read more
The Conversation recently published a nice piece by Louis and Chapman on common statistical misinterpretations and how they can be avoided. Here is summary of the main points: Problem Reason Solution 1. Assuming small differences are meaningful Most small differences are due to chance, not meaningful differences Ask for the margin of error (ie. half of the 95% CI): if
Read more
My last two posts have shown how to perform an independent t-test in the R programming language and the Python programming language. For those of you who are familiar with statistics, you likely know that an independent t-test is equivalent to performing an one-way analysis of variance on the data. What you may not have realised is that both these
Read more
In a previous post we learned how to perform an independent t-test in R to determine whether a difference between two groups is important or significant. In this post we will learn how to perform the same test using the Python programming language. Along the way we will learn a few things about t distributions and calculating confidence intervals. dataset.In
Read more
As scientists, we often want to know if the difference between two groups is important or significant. For example, you may have data on leg strength from students who came to class wearing dress shoes or running shoes. How would you decide if there was a difference in strength between these two groups? How would you quantify the size of
Read more