Statistics Without Maths for Psychology

Product Information

Basics Starting SPSS Working with data Data entry Saving your data Inputting data for between-participants and within-participants designs Within-participants designs Chapter overview Visualising the design Meaning of analysis of variance SPSS: performing a one-way ANOVA Descriptive statistics Planned comparisons Controlling for multiple testing Post-hoc tests Repeated-measures ANOVA SPSS: instructions for repeated-measures ANOVA The purpose of linear regression SPSS: drawing the line of best fit SPSS: linear regression analysis Multiple regression Chapter overview Introduction Sources of variance Designs suitable for factorial ANOVA ANOVA terminology Two between-participants independent variables SPSS: analysis of two between-participants factors Two within-participants variables SPSS: ANOVA with two within-participants factors One between- and one within-participants variable SPSS: ANOVA with one between-participants factor and one within-participants factor

Analysis of two conditions SPSS: for an independent t-test SPSS: two samples repeated-measures design – paired t-test A measure of difference A correlation coefficient An equivalent statistic to Fisher’s Exact Probability Test A CV value Pearson Education Limited Edinburgh Gate Harlow Essex CM20 2JE England and Associated Companies throughout the world Visit us on the World Wide Web at: www.pearsoned.co.uk First published 1999 Second edition published 2002 Third edition published 2004 Fourth edition published 2007 Fifth edition published 2011 © Pearson Education Limited 1999, 2011 The rights of Christine P. Dancey and John Reidy to be identified as authors of this work have been asserted by them in accordance with the Copyright, Designs and Patents Act 1988. All rights reserved. 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 either the prior written permission of the publisher or a licence permitting restricted copying in the United Kingdom issued by the Copyright Licensing Agency Ltd, Saffron House, 6–10 Kirby Street, London EC1N 8TS. All trademarks used herein are the property of their respective owners. The use of any trademark in this text does not vest in the author or publisher any trademark ownership rights in such trademarks, nor does the use of such trademarks imply any affiliation with or endorsement of this book by such owners. Pearson Education is not responsible for the content of third party internet sites. ISBN: 978-0-273-72602-9 British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library Library of Congress Cataloging-in-Publication Data Dancey, Christine P. Statistics without maths for psychology / Christine P. Dancey, John Reidy. — 5th ed. p. cm. ISBN 978-0-273-72602-9 (pbk.) 1. SPSS for Windows. 2. Mathematical statistics. 3. Psychology—Statistical methods. I. Reidy, John. II. Title. BF39.D26 2011 150.7′27—dc22 2010053187 10 14 Companion website We would urge you to make as much use as possible of the resources available to you on the companion website. When you get on to the site you will see that it is broken down into resources for each chapter. For each chapter you will find SPSS Statistics dataset files which are simply the data for the examples that we provide in each chapter. You can access these to ensure that you have input data correctly or so that you can carry out the same analyses that we present in each chapter to make sure that you get the same results. Also, on the website you will find additional multiple choice questions. If you find that you have made mistakes in the multiple choice questions provided in the book you should go back through the chapter and try to make sure that you fully understand the concepts presented. It wouldn’t make sense for you to then test yourself using the same multiple choice questions and so we have provided the additional ones on the companion website. As another means of testing yourself and to help you actively learn we provide additional SPSS Statistics exercises for each chapter and a step-by-step guide to the analysis to conduct on this data and how to interpret the output. Finally, you will find links to interesting and useful websites which are relevant to the concepts being covered in each chapter.

Find more by...

Tables Tables on pages 78 and 117 from Effects of physical positions on sleep architectures and post-nap functions among habitual nappers, Biological Psychology, 83, 207–13 (Zhao, D., Zhang, Q., Fu, M., Tang, Y. and Zhao, Y. 2010). With permission from Elsevier; Table on page 201 from Counting on Working Memory When Learning to Count and to Add: A Preschool Study, Developmental Psychology, 45 (6), 1630–1643 (Noël, P. 2009), Copyright © 2009 by the American Psychological Association. Reproduced with permission. The official citation that should be used in referencing this material is doi:10.1037/a0016224. No further reproduction or distribution is permitted without written permission from the American Psychological Association; Table on page 202 from Perceived stigma, illness intrusiveness and quality of life in men and women with irritable bowel syndrome, Psychology, Health and Medicine, 7 (4), 381–95 (Dancey, C.P., Hutton-Young, S.A., Moye, S. and Devins, G.M. 2002), Reprinted by permission of the publisher (Taylor & Francis Ltd, http://www.informaworld.com); Table on page 227 from Inferencing processes after right hemisphere brain damage: maintenance of Chapter overview Bivariate correlations SPSS: bivariate correlations – Pearson’s r SPSS: obtaining a scattergram matrix First- and second-order correlations SPSS: partial correlations – Pearson’s r Patterns of correlations

Christine P. Dancey and John Reidy ‘Excellent integration of design issues, statistical analysis and SPSS…An essential purchase for all social science undergraduates, particularly those who are anxious about statistics’. The tests you have used so far have involved calculations on sets of scores obtained from participants. Sometimes, however, we have categorical data (i.e. data in the form of frequency counts). For example, let’s imagine that we ask a sample of farmers (actually 544 of them) which of four pig pictures they prefer for a ‘save our bacon’ campaign. We would simply record how many chose picture 1, how many chose picture 2, and so on. The data would be frequency counts. Table 9.1 shows the sort of results we might obtain. Probability The standard normal distribution Applying probability to research Sampling distributions Confidence intervals and the standard error SPSS: obtaining confidence intervals Error bar charts Overlapping confidence intervals SPSS: generating error bar charts Confidence intervals around other statistics We wrote this book primarily for our students, most of whom disliked mathematics, and could not understand why they had to learn mathematical formulae when their computer software performed the calculations for them. They were not convinced by the argument that working through calculations gave them an understanding of the test – neither were we. We wanted them to have a conceptual understanding of statistics and to enjoy data analysis. Over the past decade we have had to adapt our teaching to large groups of students, many of whom have no formal training in mathematics. We found it was difficult to recommend some of the traditional statistics textbooks – either they were full of mathematical formulae, and perceived by the students as dull or boring, or they were simple, statistical cookbook recipes, which showed them how to perform calculations, but gave them no real understanding of what the statistics meant. We therefore decided to write this book, which seeks to give students a conceptual understanding of statistics while avoiding the distraction of formulae and calculations. Another problem we found with recommending statistics textbooks was the over-reliance on the probability value in the interpretation of results. We found it difficult to convince them to take effect size, and confidence intervals, into consideration when the textbooks that were available made no mention of the debates around hypothesis testing, but simply instructed students to say p < 0.05 is significant and p > 0.05 is not significant! We hope in writing this book that students will become more aware of such issues. We also wanted to show students how to incorporate the results of their analysis into laboratory reports, and how to interpret results sections of journal articles. Until recently, statistics books ignored this aspect of data analysis. Of course, we realise that the way we have written our example ‘results sections’ will be different from the way that other psychologists would write them. Students can use these sections to gain confidence in writing their own results, and hopefully they will build on them, as they progress through their course. We have tried to simplify complex, sometimes very complex, concepts. In simplifying, there is a trade-off in accuracy. We were aware of this when writing the book, and have tried to be as accurate as possible, while giving the simplest explanation. We are also aware that some students do not use SPSS (an IBM company*) for their data analysis. IBM® SPSS® Statistics, however, is the most commonly used statistical package for the social sciences, and this is why the text is tied so closely to SPSS. Students not using this package should find the book useful anyway. This edition of the book has been updated for use with SPSS version 18 and earlier. SPSS Statistics was previously known as PASW and this PASW name is still reflected in the screenshot visuals you will see; however, please note the text will always refer to SPSS. The information and explanation provided and detail in the screenshot are relevant for all versions of SPSS. For the fifth edition of this book, we have updated our chapters, and included some information about the authors of articles which we have drawn upon in the writing of this book – and have included photos of them – strictly with their permission, of course. We also asked them why they had chosen their particular research topic, and whether they had encountered any problems in the running of the experiment/study. We thought this would enrich the text. *SPSS was acquired by IBM in October 2009. The correct interpretation of the p-value Statistical tests Type I error Type II error Why set E at 0.05? One-tailed and two-tailed hypotheses Assumptions underlying the use of statistical tests SPSS: Statistics CoachIt forms a linear combination of the IVs It forms a linear combination of the DVs It is an extension of X2 It correlates the IVs with all of the DVs