DISCOVERING STATISTICS USING IBM SPSS STATISTICS

1 STATISTICS USINGIBM spss STATISTICSDISCOVERING00-Field 112/11/2012 6:04:23 PMCATISFIED CUSTOMERSC oltrane(Krista Soria)Diego(Megan Chapman)Nightshade (Dave Verkuijl)Prof Fluffypants(Sanj Choudhury)Tonks(Erica Eckert)Cody(Andrea Luu)Sams(Claudia Pama) Kamaji & Choccy(Emily Margaret-Gay)Sarah Dahl's Cat00-Field 212/11/2012 6:04:36 PM4TH EDITIONANDY FIELD STATISTICS USINGIBM spss STATISTICSDISCOVERINGAND SEX AND DRUGS AND ROCK N ROLL00-Field 312/11/2012 6:04:38 PMSAGE Publications Ltd1 Oliver s Yard 55 City RoadLondon EC1Y 1 SPSAGE Publications Teller RoadThousand Oaks, California 91320 SAGE Publications India Pvt LtdB 1/I 1 Mohan Cooperative Industrial AreaMathura RoadNew Delhi 110 044 SAGE Publications Asia-Pacific Pte Ltd3 Church Street#10-04 Samsung HubSingapore 049483 Editor: Michael CarmichaelDevelopment editor: Robin LuptonProduction editor: Ian AntcliffCopyeditor: Richard LeighProofreaders: Louise Harnby; Kate Harrison; Anna Gilding.

2 Jennifer HinchliffeIndexer: David RudeforthMarketing manager: Ben Griffin-SherwoodCover design: Wendy ScottTypeset by:Printed by: Andy Field 2013 First edition published November 2002 Second edition published 2005 Third edition published 2009 Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act, 1988, this publication may be reproduced, stored or transmitted in any form, or by any means, only with the prior permission in writing of the publishers, or in the case of reprographic reproduction.

3 In accordance with the terms of licences issued by the Copyright Licensing Agency. Enquiries concerning reproduction outside those terms should be sent to the of Congress Control Number: 2012944559 British Library Cataloguing in Publication dataA catalogue record for this book is available from the British LibraryISBN 978-1-4462-4917-8 ISBN 978-1-4462-4918-5 (pbk)00-Field 412/11/2012 6:04:38 PMvCONTENTSP reface xixHow to use this book xxvAcknowledgements xxxDedication xxxiiSymbols used in this book xxxivSome maths revision xxxvi 1

4 Why is my evil lecturer forcing me to learn STATISTICS ? 1 What will this chapter tell me? 1 What the hell am I doing here? I don t belong here 2 The research process 3 Initial observation: finding something that needs explaining 4 Generating theories and testing them 4 Collect data to test your theory 7 Variables 7 Measurement error 11 Validity and reliability 12 Correlational research methods 13 Experimental research methods 14 Randomization 18 Analysing data 19 Frequency distributions 20

5 The centre of a distribution 21 The dispersion in a distribution 24 USING a frequency distribution to go beyond the data 28 Fitting statistical models to the data 32 Reporting data 34 Dissemination of research 34 Knowing how to report data 35 Some initial guiding principles 35 Brian s attempt to woo Jane 37 What next? 37 Key terms that I ve discovered 38 Smart Alex s tasks 38 Further reading 3900-Field 512/11/2012 6:04:39 PMviDISCOVERING STATISTICS USING spss 2 Everything you never wanted to know about STATISTICS 40 What will this chapter tell me?

6 40 Building statistical models 41 Populations and samples 42 Statistical models 44 The mean as a statistical model 46 Assessing the fit of a model: sums of squares and variance revisited 46 Estimating parameters 50 Going beyond the data 51 The standard error 52 Confidence intervals 54 USING statistical models to test research questions 60 Null hypothesis significance testing 60 Problems with NHST 74 Modern approaches to theory testing 78 Effect sizes 79

7 Meta-analysis 83 Reporting statistical models 84 Brian s attempt to woo Jane 85 What next? 86 Key terms that I ve discovered 87 Smart Alex s tasks 87 Further reading 88 3 The IBM spss STATISTICS environment 89 What will this chapter tell me? 89 Versions of IBM spss STATISTICS 90 Windows versus MacOS 90 getting started 90 The data editor 91 Entering data into the data editor 98 The variable view 99 Missing values 107 Importing data 109 The spss viewer 109 Exporting spss output 113 The syntax editor 113 Saving files 115 Retrieving a file 115 Brian s attempt to woo Jane 116 What next?

8 117 Key terms that I ve discovered 117 Smart Alex s tasks 117 Further reading 120 4 Exploring data with graphs 121 What will this chapter tell me? 121 The art of presenting data 122 What makes a good graph? 122 Lies, damned lies, and .. erm .. graphs 12300-Field 612/11/2012 6:04:39 PMviiCONTENTS The spss chart builder 125 Histograms 127 Boxplots (box whisker diagrams) 131 Graphing means: bar charts and error bars 135 Simple bar charts for independent means 136 Clustered bar charts for independent means 137 Simple bar charts for related means 140 Clustered bar charts for related means 1434 Clustered bar charts for mixed designs 145 Line charts 148 Graphing relationships.

9 The scatterplot 148 Simple scatterplot 1494 Grouped scatterplot 151 Simple and grouped 3-D scatterplots 153 Matrix scatterplot 154 Simple dot plot or density plot 157 Drop-line graph 157 Editing graphs 158 Brian s attempt to woo Jane 161 What next? 161 Key terms that I ve discovered 161 Smart Alex s tasks 162 Further reading 162 5 The beast of bias 163 What will this chapter tell me?

10 163 What is bias? 164 Assumptions 165 Outliers 165 Additivity and linearity 167 Normally distributed something or other 168 Homoscedasticity/homogeneity of variance 172 Independence 176 Spotting bias 176 Spotting outliers 176 Spotting normality 179 Spotting linearity and heteroscedasticity/heterogeneity of