Publications by Michael Hunt
dplyr exercise
Adapted and extended from Chapter 3 of Getting Started with R by Beckerman, Childs and Petchey Data Management, manipulation and exploration using functions from dplyr In this exercise we will use the compensation data set, which has 40 observations of the root stock mass and mass of fruit harvested, for apple trees in both grazed and ungrazed c...
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Tidy data
Adapted and extended from Chapter 2 of Getting Started with R by Beckerman, Childs and Petchey. The bird dataset in the exercise is from Mark Gardener’s Statistics for Ecologists using R and Excel Introduction In the following you are intended to write a script of your own, using the snippets of code in this instruction set. As you come to eac...
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model_simplification
This exercise sheet is heavily indebted to Michael Crawley’s Statistics: An introduction using R, 2nd Ed, Wiley. Published in 2015 this emphasises statistics over R (in fact, much of the R he presents would be better written using tidyverse code). It is very useful and is at a higher level than Beckerman, Childs and Petchey’s Getting Started ...
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Power
This topic is all about how to design our studies such that they are likely to detect an effect, whether that is a correlation or a difference, if there really is one there to be detected. If there were, and we didn’t that would be a shame (and a waste of time and money and possibly an ethical hoohah). In what follows we focus on a simple study...
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ANOVA
Material used from Chapter One of Grafen and Hails: Modern Statistics for the Life Sciences What is ANOVA? The basic principles of ANOVA In a simple case we consider the comparison of three means. This is done by the analysis of variance (ANOVA). In this case we will go through an example in detail and work out all the mechanics, but once we ha...
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ak_analysis
This script is an analysis of my forms data for the honours project on…. We will look to see if there is any evidence in the sample data that use of the marine gym makes a difference to scores on the wellness, nr6 and nep scales. In doing this we will acknowledge that the data is ordinal in character but nevertheless use a repeated measures ANO...
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Correlation
This guide to correlation is heavily based on the very helpful chapter in Statistics, by David Freedman, Robert Pisani, Roger Purves and Ani Adhikari, 2nd ed., Norton. Correlation The notable statistician Karl Pearson (1857 - 1936) carried out a study to investigate the resemblance between children and their parents. As part of the study, Pearso...
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Statistics primer
1 A primer in statistics Based on the very helpful revision chapter in Modern Statistics for the Life Sciences, Alen Grafen and Rosie Hails, OUP. 1.1 Populations and samples It is rarely possible to get an exact answer to a question. Normally we have to make do with an estimate, and this may vary from a rough estimate to a more precise one. One ...
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Model selection
Model Selection In this example we take data in which we have measured the total volume, diameter and height at a fixed distance of 1.5 m from the ground of 20 trees. We want to see which combination of diameter, height or both is best for predicting volume of wood in trees. If either or both of these can do so with reasonable precision then that...
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chi-square test
A chi-square analysis is used when our data are in the form of raw counts for two or more categorical groups eg yellow peas or green pea seeds, survival rate of mice if they took drug A or took drug B, etc. Each independent observation must definitely belong to either one group or the other, and there must be no replicates. That is, for each cate...
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