Statistics for Terrified Biologists

Helmut F. van Emden

• Publisher: Wiley-Blackwell
• Year: 2019
• ISBN:
  9781119563686
• Edition: 2
• Topic: Medicine
• Subtopic: Biostatistics

Makes mathematical and statistical analysis understandable to even the least math-minded biology student

This unique textbook aims to demystify statistical formulae for the average biology student. Written in a lively and engaging style, Statistics for Terrified Biologists, 2 nd Edition draws on the author's 30 years of lecturing experience to teach statistical methods to even the most guarded of biology students. It presents basic methods using straightforward, jargon-free language. Students are taught to use simple formulae and how to interpret what is being measured with each test and statistic, while at the same time learning to recognize overall patterns and guiding principles. Complemented by simple examples and useful case studies, this is an ideal statistics resource tool for undergraduate biology and environmental science students who lack confidence in their mathematical abilities.

Statistics for Terrified Biologists presents readers with the basic foundations of parametric statistics, the t-test, analysis of variance, linear regression and chi-square, and guides them to important extensions of these techniques. It introduces them to non-parametric tests, and includes a checklist of non-parametric methods linked to their parametric counterparts. The book also provides many end-of-chapter summaries and additional exercises to help readers understand and practice what they've learned.

• Presented in a clear and easy-to-understand style
• Makes statistics tangible and enjoyable for even the most hesitant student
• Features multiple formulas to facilitate comprehension
• Written by of the foremost entomologists of his generation

This second edition of Statistics for Terrified Biologists is an invaluable guide that will be of great benefit to pre-health and biology undergraduate students.

1
How to use this book

Chapter features

• Introduction
• The text of the chapters
• What should you do if you run into trouble?
• Elephants
• The numerical examples in the text
• Boxes
• Spare–time activities
• Executive summaries
• Why go to all that bother?
• The bibliography

Introduction

Don't be misled! This book cannot replace effort on your part. All it can aspire to do is to make that effort effective. The detective thriller only succeeds because you have read it too fast and not really concentrated – with that approach, you'll find this book just as mysterious.

In fact, you may not get very far if you just read this book at any speed! You will only succeed if you interact with the text, and how you might do this is the topic of most of this chapter.

The text of the chapters

The chapters, particularly 2–8, develop a train of thought essential to the subject of analysing biological data. You just have to take these chapters in order and quite slowly. There is only one way I know for you to maintain the concentration necessary to comprehension, and that is for you to make your own summary notes as you go along.

My Head of Department when I first joined the staff at Reading used to define a university lecture as ‘a technique for transferring information from a piece of paper in front of the lecturer to a piece of paper in front of the student, without passing through the heads of either’. That's why I stress making your own summary notes. You will retain very little by just reading the text; you'll find that after a while you've been thinking about something totally different while ‘reading’ several pages – we've all been there! The message you should take from my Head of Department's quote above is that just repeating in your writing what you are reading is little better than taking no notes at all: the secret is to digest what you have read and reproduce it in your own words and in summary form. Use plenty of headings and subheadings, boxes linked by arrows, cartoon drawings, etc. Another suggestion is to use different coloured pens for different recurring statistics, such as variance and correction factor. In fact, use anything that forces you to convert my text into as different a form as possible from the original; that will force you to concentrate, to involve your brain and to make it clear to you whether or not you have really understood that bit in the book so that it is safe to move on.

The actual process of making the notes is the critical step – you can throw the notes away at a later stage if you wish, though there's no harm in keeping them for a time for revision and reference.

So DON'T MOVE ON until you are ready. You'll only undo the value of previous effort if you persuade yourself that you are ready to move on when in your heart of hearts you know you are fooling yourself!

A key point in the book is Figure 7.5 on p. 64. Take real care to lay an especially good foundation up to there. If you really feel at home with this diagram, it is a sure sign that you have conquered any hang‐ups and are no longer a ‘terrified biologist’.

What should you do if you run into trouble?

The obvious first step is to go back to the point in the book where you last felt confident, and start again from there.

However, it often helps to see how someone else has explained the same topic, so it's a good idea to have a look at the relevant pages of a different statistics text (see Appendix D for some suggestions). You could also look up the topic on the Internet, where many statisticians have put articles and their lectures to students.

A third possibility is to see if someone can explain things to you face to face. Do you know or have access to someone who might be able to help? If you are at university, it could be a fellow student or even one of the staff. The person who tried to teach statistics to my class at university failed completely as far as I was concerned, but later on I found he could explain things to me quite brilliantly in a one‐to‐one situation.

Elephants

At certain points in the text you will find the sign of the elephant, i.e.

.

They say ‘elephants never forget’ and the symbol means just that: NEVER FORGET! I have used it to mark some key statistical concepts which, in my experience, people easily forget and as a result run into trouble later on and find it hard to see where they have gone wrong. So, take it from me that it is really well worth making sure these matters are firmly embedded in your memory.

The numerical examples in the text

As stated in the Preface to the First Edition, I soon learnt that biologists don't like x. For some reason they prefer a real number but are more prepared to accept, say, 45 as representing any number than they are an x! Therefore, in order to avoid ‘algebra’ as far as possible, I have used actual numbers to illustrate the working of statistical analyses and tests. You probably won't gain a lot by keeping up with me on a hand calculator as I describe the different steps of a calculation, but you should make sure at each step that you understand where each number in a calculation has come from and why it has been included in that way.

When you reach the end of each worked analysis or test, however, you should go back to the original source of the data in the book and try to rework on a hand calculator the calculations which follow from just those original data. Try not to look up later stages in the calculations unless you are irrevocably stuck, and then use the executive summary (if there is one at the end of the chapter) rather than the main text.

Boxes

There will be a lot of individual variation among readers of this book in the knowledge and experience of statistics they have gained in the past, and in their ability to grasp and retain statistical concepts. At certain points, therefore, some will be happy to move on without any further explanation from me or any further repetition of calculation procedures.

For those less happy to take things for granted at such points, I have placed the material and calculations they are likely to find helpful in boxes in order not to hold back or irritate the others. Calculations in the boxes may prove particularly helpful if, as suggested above, you are reworking a numerical example from the text and need to refer to a box to find out why you are stuck or perhaps where you went wrong.

Spare‐time activities

These are numerical exercises you should be equipped to complete by the time you reach them at the end of several of the chapters.

That is the time to stop and do them. Unlike the within‐chapter numerical examples, you should feel quite free to use any material in previous chapters or executive summaries to remind you of the procedures involved and guide you through them. Use a hand calculator and remember to write down the results of intermediate calculations. This will make it much easier for you to detect where you went wrong if your answers do not match the solution to that exercise given in Appendix C. Do read the beginning of that appendix early on: it explains that you should not worry or waste time recalculating if your numbers are similar, even if they are not identical. I can assure you, you will recognise – when you compare your figures with the ‘solution’ – if you have followed the statistical steps of the exercise correctly; you will also immediately recognise if you have not.

Doing these exercises conscientiously with a hand calculator or spreadsheet, and when you reach them in the book rather than much later, is really important. They are the best things in the book for impressing the subject into your long‐term memory and for giving you confidence that you understand what you are doing.

The authors of most other statistics books recognise this and also include exercises. If you're willing, I would encourage you to gain more confidence and experience by going on to try the methods as described in this book on their exercises.

By the way, a blank spreadsheet such as Excel makes a grand substitute for a hand calculator, with the added advantage that repeat calculations (e.g. squaring numbers) can be copied and pasted from the first number to all the others.

Executive summaries

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