Paul J. Mitchell

Experimental Design and Statistical Analysis for Pharmacology and the Biomedical Sciences


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coming along now you've been in the big wide world?’ was met with a mixture of dismay and disdain, not to say contempt for mentioning the S word! The ensuing conversation quickly dispelled any thoughts on my part regarding their progress and so I quickly put together an intense four‐week package, which covered all my statistics lectures and hands‐on data analysis workshops to get them up to speed. The feedback I received suggested that delivering such material in such a short period was successful, but one important component was missing; they had no access to a suitable concise textbook covering descriptive and inferential statistics suitable for undergraduate pharmacology students. Indeed their major complaint was that currently available textbooks were either focused on statistical theory (suitable only for highly competent students of mathematics) or were simply user guides for statistical software packages; both of which were totally inappropriate for students who simply wanted to know which statistical tests they had to use to analyse different types of experimental data. In short, they needed a concise ‘textbook’ book, which showed them how to use statistics as a tool with which they could analyse their experimental data and arrive at appropriate conclusions, thereby revealing the relationship of their data to the real world. So, it seems obvious to me that the first group of individuals that I should thank, and you, dear reader, should blame for kick‐starting this project which has resulted in the contents of this book, are the infamous seven final year pharmacology students from 2016: Charlotte Bell, Charlotte Day, Sam Groom, James Miles (yes, that cocky bugger), Katy Murrell, Gemma Wilkinson, and Alex Williams – according to my latest information most if not all have now completed (or nearly so) their subsequent PhD studies and are now forging research careers on their own (and most notably without my help!). If this book is in any way successful, then clearly you seven should be held totally accountable!

      Of course, when you embark on a project that is clearly not your day job, then you need a lot of support to help you to find the time in the working day that enables you to turn that germ of an idea into fruition. My sincere thanks to all my colleagues in the Department of Pharmacy and Pharmacology at the University of Bath that in many, diverse, ways have enabled me to focus on putting this manuscript together, that have humoured me while I've ranted on regarding the statistical inadequacies in the scientific press or listened quietly while I've bombarded them with different ideas on how to describe quite complex statistical issues that an inexperienced undergraduate student may (hopefully) understand. Most importantly, my thanks to Profs Steve Ward and Roland Jones who agreed for me to move my teaching duties around that created gaps in my teaching load, which allowed me to concentrate on writing. This book is full of data examples, which, I hope, will enable the reader to understand more‐fully descriptive and inferential statistics and to envisage statistics in action. Most of the data examples are my own, and for all other examples I am very grateful to Dr Malcolm Watson. I must also thank Prof Steve Husbands and Dr Christine Edmead for their helpful comments, encouragement, and suggestions after reading the first completed draft version of the manuscript; of course, considering Steve is a medicinal/organic chemist, who (by his own admission) failed to understand anything described in the book, his comments were totally ignored!

      For the last 15–20 years or so, I have worked very closely with Prof John Kelly, Department of Pharmacology and Therapeutics, NUIGalway, during which we have tried, successfully it must be said, to develop a fully integrated series of lectures and workshops to teach undergraduate and postgraduate students in pharmacology, neuropharmacology, toxicology, and drug discovery the vagaries of robust experimental design and statistical analysis. I still travel to Galway every year to expose John's postgraduate students to an English sense of humour in my attempt to run hands‐on statistical workshops – I must be doing OK as John keeps inviting me back! My sincere thanks to John for all the support and encouragement he has given me during that time and to other colleagues in Galway, notably Ambrose O’Halloran and Sandra O'Brien, who were instrumental in preparing the initial versions of the lectures, which I now subject my own students to back in Bath and which are closely aligned to the contents and flavour of this book.

      During the life of this project, I have worked closely at various times with the management team for the British Pharmacological Society and I would like to convey my thanks to David James (Executive Director, Business Development) for his initial help and advice to get this project off the ground, and latterly to Katherine Wilson (Director, Research Dissemination) and Lee Page (Head of Education and Engagement) for their help and advice on ‘what to do next’!

      My career in pharmacology has taken me from the pharmaceutical industry with Beecham Pharmaceuticals in the 1970s and 1980s, through my PhD studies at the University of Bath in the latter half of the 1980s (under the invaluable supervision of Prof Peter Redfern), then back to the industry with Wyeth‐Ayerst in 1989 before returning to the University of Bath in 1995 where I have remained ever since. Throughout that time in industry and academia, I have worked with a wide range of wonderful, highly skilled, individuals and made life‐long friends too numerous to name individually here (but you should all know who you are on both sides of the Atlantic Ocean). I shall remain eternally grateful for all your help, guidance, encouragement, patience, comments, critique (usually constructive), and tutelage throughout my career in pharmacology.

      You will note that at the end of most of the chapters in this book, I have been able to provide screenshots from the software packages that I used to analyse the examples used in the book. This was for two purposes. First, this allowed me to check my own calculations for every single example and statistics test described herein (yes; every example has been analysed in the good old‐fashioned way by hand and a good calculator – good God, what a geek I hear you cry – and you'd be right as my academic colleagues keep telling me!), and second, I hope that when you run your own data analysis you will now be forewarned about what to expect (and not be surprised) by the output from the software you have used. To that end, I am most grateful to the software companies concerned for permission to reproduce screenshots from their software. Consequently, screenshots from GraphPad – Prism®Statistics software version 8.2 and above are printed with permission of GraphPad Software, San Diego, California, USA; screenshots from MiniTab software version 18 and above are printed with permission of MiniTab, LLC; screenshots from InVivoStat are reprinted with permission of the InVivoStat team (specifically Simon Bate); and finally screenshots from IBM® SPSS® Statistics software (SPSS) version 26 and above are printed with permission from International Business Machines Corporation (IBM).

      I've been very lucky to have a number of very close friends who have remained loyal regardless of where my career has taken me, so a special mention to Dave Bragg (‘Braggy’), John Clapham (JC), and Alan Rainbird for your unwavering friendship (which I value more than words can ever express) since we first met over 45 years ago, John Kelly (see above), and more recently to Kevin McDermott for dragging me out most Saturday mornings to the golf course to clear our heads for a few therapeutic hours away from the stress of our professional lives, see you on the first tee mate!

      Finally (!), all my love to my wife Angela and my children Matthew and Samantha – how you all ever put up with such a cantankerous old git as myself (especially during the last four years or so while I worked on this manuscript) I shall never know. You are all my rock, and I will always be forever grateful.