open university press designing and reporting experiments in psychology apr 2008

www.openup.co.uk Cover design Hybert Design • www.hybertdesign.com Peter Harris Designing and Reporting Experiments in Psychology Designing and Reporting Experiments in Psychology Third Edition Harris Designing and Reporting Experiments in Psychology Third Edition This book will help undergraduate psychology students to write practical reports of experimental and other quantitative studies in psychology. It is designed to help with every stage of the report writing process including what to put in each section and recommendations for formatting and style. It also discusses how to design a study, including how to use and report relevant statistics. As such, the book acts both as an introduction and reference source to be used throughout an undergraduate course. Key features of the new edition include: ● New pedagogy. Website icons within the text reference an enhanced website, www.openup.co.uk/harris, and ‘Common Mistake’ icons highlight common errors students should avoid. Statistics icons make reference to two key statistics books* where students can find more detailed information. A further icon indicates the presence of relevant commentary at the end of the book for more advanced students ● Discussion of how to write up different forms of quantitative study and report relevant statistics ● Improved self-testing. There are diagnostic questions (with answers at the end of the book) as well as fifty self-assessment questions within the text to aid student learning. Chapters in Part Two contain a list of methodological and statistical concepts covered that will help students to consolidate their knowledge ● A completely revised section on how to find and cite references plus current information on how to cite electronic references, incorporating the new APA guidelines ● Advice on the ethics of conducting research on the Internet * The statistics books referenced are SPSS Survival Manual 3/e by Julie Pallant and Learning to Use Statistical Tests in Psychology 3/e by Judith Greene and Manuela d’Oliveira, both published by Open University Press. However, this book is designed for use with any statistics textbook. Peter Harris is Senior Lecturer in Psychology at the University of Sheffield. Previously, he has worked at the universities of Sussex, Hertfordshire and Nottingham. He collaborates with colleagues at the universities of British Columbia, Pittsburgh and Maastricht. His principal research interests are in social and health psychology. Third Edition Designing and reporting experiments in psychology 9780335221783_1_pre.qxd 3/13/08, 2:44 PM1 Allie 9780335221783_1_pre.qxd 3/13/08, 2:44 PM2 Designing and reporting experiments in psychology THIRD EDITION Peter Harris Open University Press 9780335221783_1_pre.qxd 3/13/08, 2:44 PM3 Open University Press McGraw-Hill Education McGraw-Hill House Shoppenhangers Road Maidenhead Berkshire England SL6 2QL email: enquiries@openup.co.uk world wide web: www.openup.co.uk and Two Penn Plaza, New York, NY 10121-2289, USA First published 2008 Copyright © Peler Harris All rights reserved. Except for the quotation of short passages for the purpose of criticism and review, no part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior written permission of the publisher or a licence from the Copyright Licensing Agency Limited. Details of such licences (for reprographic reproduction) may be obtained from the Copyright Licensing Agency Ltd of Saffron House, 6 –10 Kirby Street, London, EC1N 8TS. A catalogue record of this book is available from the British Library ISBN-13: 978-0-335-22178-3 ISBN-10: 0-335-22178-5 Library of Congress Cataloging-in-Publication Data CIP data applied for Typeset by Graphicraft Limited, Hong Kong Printed in Great Britain by Bell & Bain Ltd, Glasgow Fictitious names of companies, products, people, characters and/or data that may be used herein (in case studies or in examples) are not intended to represent any real individual, company, product or event. 9780335221783_1_pre.qxd 3/13/08, 2:44 PM4 To Antony and Richard, my sons 9780335221783_1_pre.qxd 3/13/08, 2:44 PM5 9780335221783_1_pre.qxd 3/13/08, 2:44 PM6 Contents Contents of the Web site xiii Preface xvii To students xviii How to use this book xix To tutors xxi Part 1 Writing reports 1 1 Getting started 3 1.1 Experienced students, inexperienced students, and the report 6 1.2 Writing the report 8 1.3 The importance of references in text 9 1.4 The practical report and the research paper 11 1.5 Finding references for your introduction 14 1.5.1 How to structure your reading and what to look for 14 1.5.2 Generating potential references 15 1.5.3 Locating the references 16 1.5.4 Rubbish and temptation on the Internet 18 1.6 Ethics 18 1.7 The rest of the book and the book’s Web site 19 2 The INTRODUCTION section 20 2.1 The first part of the introduction: reviewing the background to your study 21 9780335221783_1_pre.qxd 3/13/08, 2:44 PM7 2.2 Inexperienced students, experienced students, and the introduction 22 2.3 Your own study 26 3 The METHOD section 30 3.1 The design subsection 32 3.2 The participants subsection 34 3.3 The apparatus or materials subsection 37 3.4 The procedure subsection 39 3.5 Interacting with and instructing participants 42 3.6 Optional additional subsections of the method 44 3.6.1 Pilot test 45 3.6.2 Ethical issues 45 3.6.3 Statistical power 45 3.7 Writing a method when your study is not an experiment 46 4 The RESULTS section 48 4.1 Describing the data: descriptive statistics 49 4.2 Analysing the data: inferential statistics 52 4.3 An example results section 54 4.4 Nine tips to help you avoid common mistakes in your results section 56 4.5 Rejecting or not rejecting the null hypothesis 58 4.6 Reporting specific statistics 59 4.6.1 Chi-square, χ 2 60 4.6.2 Spearman rank correlation coefficient (rho), r s 60 4.6.3 Pearson’s product moment correlation coefficient, r 60 4.6.4 Mann-Whitney U test, U 61 4.6.5 Wilcoxon’s Matched-Pairs Signed-Ranks Test, T 61 4.6.6 Kruskal-Wallis one-way analysis of variance, H 61 4.6.7 Friedman’s ANOVA, χ 2 r 62 4.6.8 The independent t test, t 62 4.6.9 The related t test, t 62 4.6.10 Analysis of variance (ANOVA), F 63 4.6.11 Four tips to help you avoid common mistakes when reporting ANOVA 65 4.6.12 Linear regression 66 4.6.13 Statistics of effect size 69 4.7 What you can find on the book’s Web site 70 4.8 What you can find in the statistics textbooks paired with this book 70 viii Contents 9780335221783_1_pre.qxd 3/13/08, 2:44 PM8 5 The DISCUSSION section 72 5.1 How well do the findings fit the predictions? 75 5.2 What do the findings mean? 75 5.3 What are the implications of these findings? 78 5.4 What to do when you have been unable to analyse your data properly 79 5.5 External validity: the generalizability of findings 79 5.6 Six tips to help you to avoid some common failings in the discussion 81 5.7 Two example discussion sections 82 5.7.1 The cheese and nightmare experiment 82 5.7.2 The mnemonic experiment 83 5.8 Writing a discussion when your study is not an experiment 85 6 The TITLE and ABSTRACT 87 6.1 The title 87 6.2 The abstract 88 7 REFERENCES and APPENDICES 92 7.1 The references section 92 7.2 General rules for the references section 93 7.3 An example references section 93 7.4 Key to the example references section 94 7.5 Electronic references 95 7.5.1 Published material obtained electronically 96 7.5.2 Unpublished material obtained electronically 97 7.6 Appendices 98 8 Producing the final version of the report 100 8.1 Writing style 100 8.2 Definitions and abbreviations 102 8.3 References in the text 102 8.3.1 Using et al. properly 104 8.3.2 Quotations and plagiarism 105 8.4 Tables and figures 107 8.5 Graphing data 109 8.5.1 One IV with two levels 110 8.5.2 Error bars 111 8.5.3 One IV with more than two levels 113 8.5.4 More than one IV 113 8.5.5 Tips to help you produce better graphs 115 8.6 Drafting the report 116 8.7 Producing the final version 117 Contents ix 9780335221783_1_pre.qxd 3/13/08, 2:44 PM9 [...]... main effects, interactions and graphing interactions C1 Main effects of independent variables C2 Interactions between independent variables C3 Interpreting main effects and interactions C4 Interactions qualify main effects C5 Graphing interactions C6 Graphing three-way interactions C7 A list of the possible effects in designs with two, three, or four IVs D Rules for writers E Reporting studies that include... 12.2 Power 12.2.1 Estimating power 12.2.2 Increasing the power of our experiments 12.3 Effect size and power: reporting and interpreting findings 12.3.1 Reporting for those who do not know how to calculate power or effect size statistics 12.3.2 Reporting for those who have been taught how to calculate power or effect size statistics 195 198 199 200 201 202 Consolidating your learning 13 More advanced experimental... have randomized G5 Include manipulation checks G6 Measure process variables G7 Think carefully about when to randomize, especially when you are not blind to condition H Some issues to consider in the results sections of your later reports and projects H1 The opening paragraph(s): setting the scene H2 Reporting the descriptive and inferential statistics H3 Including statistics of effect size and confidence... http://mcgraw-hill.co.uk/openup/harris/ The summaries at the end of each section recapitulate the main points and so provide a useful aid to revision The Index of concepts that appears at the end of the book indicates the place in the text where each concept is introduced and defined Entries in the index are in bold print in the text You will find icons in the margin that flag up things like coverage to... advice relevant to how they now seek out information There continue to be changes in custom and practice and I have written this edition to reflect these as best I can For instance, the move in published work towards dealing with issues of power and effect size continues, as does the need, therefore, to educate and train our students in dealing with and reporting these issues Previous editions were used... material in each chapter before you move on to the next one In particular, make sure that you are comfortable with the material in Chapters 9–11 before tackling Chapters 12 and 13 To help you to develop and extend your knowledge of report writing and design, I have included a separate commentary on various issues and points in the text The commentary is designed to extend your understanding by expanding... in scientific writing You can find out more about how to reference in psychology in Chapter 8 You must reference properly in your reports and indeed in everything that you write in psychology In most cases you will be given at least some references to read for your practical As you become more experienced, however, more will be expected of you in terms of reading around the area and hunting down your own... learning and a better general understanding, and will help you to be more of an active participant than a passive reader The answers to these questions are at the rear of the book In Part 2, you will find a section at the end of each chapter to help you check your understanding and consolidate your learning If you are using either ∑ Greene and D’Oliveira’s Learning to use statistical tests in psychology. .. report writing Why? Because these elements are inextricably linked It is hard to write a good report of a study without understanding the whys and wherefores of its design In order to fully understand what is required of you in the report, therefore, it helps to have an idea of the function that the report of a study serves in the scientific world This, in turn, requires you to understand something about... Extending the number of levels on the independent variable 13.1.1 Unrelated samples IVs 13.1.2 Related samples IVs 13.2 Experimental designs with two or more independent variables 13.3 Labelling designs that have two or more independent variables 13.4 Main effects of independent variables 13.5 Statistical interactions 13.6 Analysing designs involving two or more IVs 13.7 Graphing statistical interactions . www.openup.co.uk Cover design Hybert Design • www.hybertdesign.com Peter Harris Designing and Reporting Experiments in Psychology Designing and Reporting Experiments in Psychology Third Edition Harris Designing. British Columbia, Pittsburgh and Maastricht. His principal research interests are in social and health psychology. Third Edition Designing and reporting experiments in psychology 9780335221783_1_pre.qxd. 3/13/08, 2:44 PM2 Designing and reporting experiments in psychology THIRD EDITION Peter Harris Open University Press 9780335221783_1_pre.qxd 3/13/08, 2:44 PM3 Open University Press McGraw-Hill