Medical Statistics Made Easy, 4th edition

Book Preface

This book is designed for healthcare students and professionals who need a basic knowledge of when common statistical terms are used and what they mean.
Whether you love or hate statistics, you need to have some understanding of the subject if you want to understand or critically appraise a research paper. To do this, you do not need to know how to do a statistical analysis. What you do need is to know why the test has been used and how to interpret the resulting figures.
This book does not assume that you have any prior statistical knowledge. However basic your mathematical or statistical knowledge, you will find that everything is clearly explained.
A few readers will find some of the sections ridiculously simplistic, others will find some bafflingly difficult. The
“thumbs up” grading will help you pick out concepts that suit your level of understanding.
The “star” system is designed to help you pick out the most important concepts if you are short of time.
This book is also produced for those who may be asked about statistics in an exam. Pick out the “exam tips” sections if you are in a hurry.
You can test your understanding of what you have learnt by working through extracts from original papers in the “Statistics at work” section.

About the authors

Professor Michael Harris (MB BS FRCGP MMEd) is Honorary Senior Research Fellow at the University of Exeter Medical School, UK, and Research Associate at the University of Bern, Switzerland. As well as being a General Practitioner, his roles have included medical education and being an examiner for the MRCGP.
Professor Gordon Taylor (PhD MSc BSc (Hons)) is Professor of Medical Statistics at the University of Exeter, UK. His main role is in the teaching, support and supervision of health care professionals involved in non-commercial research.

How to use this book

You can use this book in a number of ways.

If you want a statistics course

Work through from start to finish for a complete course in commonly used medical statistics.

If you are in a hurry

• Choose the sections with the most stars to learn about the commonest statistical methods and terms.
• You may wish to start with these 5-star sections: percentages (Chapter 3), mean (Chapter 4), median
(Chapter 5), standard deviation (Chapter 7), confidence intervals (Chapter 8) and P values (Chapter 9).

If you are daunted by statistics

• If you are bewildered every time someone tries to explain a statistical method, then pick out the sections with the most thumbs up symbols to find the easiest and most basic concepts.
• You may want to start with percentages (Chapter 3), mean (Chapter 4), median (Chapter 5) and mode
(Chapter 6), then move on to risk ratio (Chapter 13), incidence and prevalence (Chapter 22).

If you are taking an exam

• The “Exam Tips” give you pointers to the topics which examiners like to ask about.
• You will find these in the following sections: mean
(Chapter 4), standard deviation (Chapter 7), confidence intervals (Chapter 8), P values (Chapter 9), risk reduction and NNT (Chapter 15), sensitivity, specificity and predictive value (Chapter 20), incidence and prevalence (Chapter 22).

Test your understanding

• See how statistical methods are used in five extracts from real-life papers in the “Statistics at work” section (Chapters 23–28).
• Work out which statistical methods have been used, why, and what the results mean. Then check your understanding in our commentaries.

Glossary

Use the Glossary as a quick reference for statistical words or phrases that you do not know.

Study advice

• Go through difficult sections when you are fresh and try not to cover too much at once.
• You may need to read some sections a couple of times before the meaning sinks in. You will find that the examples help you to understand the principles.
• We have tried to cut down the jargon as much as possible. If there is a word that you do not understand, check it out in the Glossary.