SPSS survival manual

0905-prelims.QX5 7/12/04 4:30 PM Page i Bookhouse SPSS SURVIVAL MANUAL For the SPSS Survival Manual website, go to www.allenandunwin.com/spss.htm 0905-prelims.QX5 7/12/04 4:30 PM Page ii Bookhouse This is what readers from around the world say about the SPSS Survival Manual: ‘To any student who have found themselves facing the horror of SPSS after signing up for a degree in psychology—this is a godsend.’ PSYCHOLOGY STUDENT, IRELAND ‘This book really lives up to its name I highly recommend this book to any MBA student carrying out a dissertation project, or anyone who needs some basic help with using SPSS and data analysis techniques.’ BUSINESS STUDENT, UK ‘If the mere thought of statistics gives you a headache, then this book is for you.’ STATISTICS STUDENT, UK ‘ one of the most useful, functional pieces of instruction I have seen So gold stars and thanks.’ INSTRUCTIONAL DESIGNER, USA ‘ being an external student so much of my time is spent teaching myself But this has been made easier with your manual as I have found much of the content very easy to follow I only wish I had discovered it earlier.’ ANTHROPOLOGY STUDENT, AUSTRALIA ‘The strength of this book lies in the explanations that accompany the descriptions of tests and I predict great popularity for this text among teachers, lecturers and researchers.’ ROGER WATSON, JOURNAL OF ADVANCED NURSING, 2001 ‘ an excellent book on both using SPSS and statistical know how.’ LECTURER IN BUSINESS RESEARCH METHODS, UK ‘SPSS Survival Manual was the only one among loads of SPSS books in the library that was so detailed and easy to follow.’ DOCTORAL STUDENT IN EDUCATION, UK ‘My students have sung the book’s praises Teaching statistics, I usually don’t get much praise from students for any book.’ STATISTICS LECTURER, USA ‘Truly the best SPSS book on the market.’ LECTURER IN MANAGEMENT, AUSTRALIA ‘I was behind in class, I was not “getting it” and I was desperate! So I bought all the SPSS books I could find This book is the one I used Everything I needed to know and be able to was clearly explained The accompanying online database served as an example, showing me how to enter data This book will not go on my bookshelf; it will remain on my desk through my dissertation and afterwards.’ STUDENT, USA ‘This book is exactly what it claims to be— a “survival manual” It contains step by step instructions and clear explanations of how to use SPSS, how to interpret the results, and selecting appropriate tests This isn’t a statistics primer or a text on research design This is a book for those who haven’t had five stats courses and years of using SPSS If you need help using SPSS to evaluate research data— get this book A lifesaver!’ STUDENT, USA ‘I like it very much and I find it very usefel.’ SOCIOLOGY STUDENT, CZECH REPUBLIC 0905-prelims.QX5 7/12/04 4:30 PM Page iii Bookhouse SPSS SURVIVAL MANUAL A step by step guide to data analysis using SPSS for Windows (Version 12) JULIE PALLANT 0905-prelims.QX5 7/12/04 4:30 PM Page iv Bookhouse First published in 2002 This edition published in 2005 Copyright © Julie Pallant 2002, 2005 All rights reserved No part of this book may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording or by any information storage and retrieval system, without prior permission in writing from the publisher The Australian Copyright Act 1968 (the Act) allows a maximum of one chapter or 10 per cent of this book, whichever is the greater, to be photocopied by any educational institution for its educational purposes provided that the educational institution (or body that administers it) has given a remuneration notice to Copyright Agency Limited (CAL) under the Act Allen & Unwin 83 Alexander Street Crows Nest NSW 2065 Australia Phone: (61 2) 8425 0100 Fax: (61 2) 9906 2218 Email: info@allenandunwin.com Web: www.allenandunwin.com National Library of Australia Cataloguing-in-Publication entry: Pallant, Julie F (Julie Florence), 1961- SPSS survival manual : a step by step guide to data analysis using SPSS 2nd edn Bibliography Includes index ISBN 74114 478 Social sciences—Statistical methods—Computer programs I Title 005.36 Set in 10.9/13.68 pt Sabon by Bookhouse, Sydney Printed by Ligare, Sydney 10 0905-prelims.QX5 7/12/04 4:30 PM Page v Bookhouse Contents Contents Data files and website Introduction and overview Structure of this book Using this book Research tips Additional resources PART ONE Getting started xi xii xiii xiii xv xvi 1 Designing a study Planning the study Choosing appropriate scales and measures Preparing a questionnaire References 3 10 Preparing a codebook Variable names Coding responses Coding open-ended questions 12 12 14 14 Getting to know SPSS Starting SPSS Opening an existing data file Working with data files SPSS windows Menus Dialogue boxes Closing SPSS Getting help 16 16 16 17 18 22 22 24 24 PART TWO Preparing the data file Creating a data file and entering data Changing the SPSS ‘Options’ Defining the variables Entering data Modifying the data file Data entry using Excel 25 27 27 30 34 35 38 v 0905-prelims.QX5 vi 7/12/04 4:30 PM Page vi Bookhouse SPSS Survival Manual Screening and cleaning the data Step 1: Checking for errors Step 2: Finding the error in the data file Step 3: Correcting the error in the data file Reference 40 40 43 45 46 PART THREE Preliminary analyses 47 Descriptive statistics Categorical variables Continuous variables Assessing normality Checking for outliers Additional exercises References 49 49 50 53 58 62 63 Using graphs to describe and explore the data Histograms Bar graphs Scatterplots Boxplots Line graphs Editing a chart/graph Importing charts/graphs into Word documents Additional exercises 64 64 66 68 70 72 74 75 76 Manipulating the data Calculating total scale scores Transforming variables Collapsing a continuous variable into groups Collapsing the number of categories of a categorical variable Additional exercises Reference 78 78 82 85 86 88 89 Checking the reliability of a scale Details of example Interpreting the output from reliability Presenting the results from reliability Additional exercises References 90 90 92 92 93 93 0905-prelims.QX5 7/12/04 4:30 PM Page vii Bookhouse Contents 10 Choosing the right statistic Overview of the different statistical techniques The decision-making process Key features of the major statistical techniques References Summary table of the characteristics of the main statistical techniques 94 94 98 104 109 PART FOUR Statistical techniques to explore relationships among variables 113 Techniques covered in Part Four Revision of the basics References 110 113 114 119 11 Correlation Details of example Preliminary analyses for correlation Interpretation of output from correlation Presenting the results from correlation Obtaining correlation coefficients between groups of variables Comparing the correlation coefficients for two groups Testing the statistical significance of the difference between correlation coefficients Additional exercises Reference 121 122 123 125 127 128 130 12 Partial correlation Details of example Interpretation of output from partial correlation Presenting the results from partial correlation Additional exercises References 136 136 138 139 139 139 13 Multiple regression Major types of multiple regression Assumptions of multiple regression Details of example Standard multiple regression Hierarchical multiple regression Interpretation of output from hierarchical multiple regression Presenting the results from multiple regression Additional exercises References 140 141 142 144 146 155 157 158 158 159 132 135 135 vii 0905-prelims.QX5 viii 7/12/04 4:30 PM Page viii Bookhouse SPSS Survival Manual 14 Logistic regression Assumptions Details of example Data preparation: coding of responses Interpretion of output from logistic regression Presenting the results from logistic regression References 160 161 162 162 166 170 171 15 Factor analysis Steps involved in factor analysis Details of example Procedure for factor analysis Warning Presenting the results from factor analysis Additional exercises References 172 173 177 178 190 190 192 193 PART FIVE 195 Statistical techniques to compare groups Techniques covered in Part Five Assumptions Type error, Type error and power Planned comparisons/Post-hoc analyses Effect size References 195 196 198 199 201 203 16 T-tests Independent-samples t-test Paired-samples t-test Additional exercises Reference 205 205 209 213 213 17 One-way analysis of variance One-way between-groups ANOVA with post-hoc tests One-way between-groups ANOVA with planned comparisons One-way repeated measures ANOVA Additional exercises References 214 215 220 223 227 228 18 Two-way between-groups ANOVA Details of example Interpretation of output from two-way ANOVA Presenting the results from two-way ANOVA Additional analyses if you obtain a significant interaction effect Additional exercises References 229 229 233 236 236 237 238 0905-prelims.QX5 7/12/04 4:30 PM Page ix Bookhouse Contents 19 Mixed between-within subjects analysis of variance Details of example Interpretation of output from mixed between-within ANOVA Presenting the results from mixed between-within ANOVA References 239 239 244 246 246 20 Multivariate analysis of variance Details of example Assumption testing Performing MANOVA Interpretation of output from MANOVA Presenting the results from MANOVA Additional exercises References 247 248 249 255 258 261 261 261 21 Analysis of covariance Uses of ANCOVA Assumptions of ANCOVA One-way ANCOVA Two-way ANCOVA References 263 263 265 267 277 285 22 Non-parametric statistics Summary of techniques covered in this chapter Chi-square Mann-Whitney U Test Wilcoxon Signed Rank Test Kruskal-Wallis Test Friedman Test Spearman’s Rank Order Correlation Additional exercises References 286 286 287 291 292 294 296 297 298 299 Appendix Details of data files Part A: Materials for survey.sav Part B: Materials for experim.sav Part C: Materials for staffsurvey.sav Part D: Materials for sleep.sav 300 302 307 308 311 Recommended references 313 Index 316 ix 0905-prelims.QX5 7/12/04 4:30 PM Page x Bookhouse 0905-section3.QX5 304 7/12/04 4:12 PM Page 304 SPSS Survival Manual Total scale scores included in survey.sav Full variable name SPSS variable name Coding instructions Total Optimism toptim Total Mastery tmast Total Positive Affect tposaff Total Negative Affect tnegaff Total Life Satisfaction tlifesat Total Perceived Stress tpstress Total Self-esteem tslfest reverse items op2, op4, op6 add all scores op1 to op6 range to 30 reverse items mast1, mast3, mast4, mast6, mast7 add all items mast1 to mast7 range to 28 add items pn1, pn4, pn6, pn7, pn9, pn12, pn13, pn15, pn17, pn18 range 10 to 50 add items pn2, pn3, pn5, pn8, pn10, pn11, pn14, pn16, pn19, pn20 range 10 to 50 add all items lifsat1 to lifsat5 range to 35 reverse items pss4, pss5, pss7, pss8 add all items pss1 to pss10 range 10 to 50 reverse items sest3, sest5, sest7, sest9, sest10 add all items sest1 to sest10 range 10 to 40 Total Social Desirability tmarlow reverse items m6 to m10 (recode true=1, false=0) add all items m1 to m10 range to 10 Total Perceived Control of Internal States tpcoiss New Education categories educ2 Age group categories Age group categories agegp3 agegp5 reverse items pc1, pc2, pc7, pc11, pc15, pc16 add all items pc1 to pc18 range 18 to 90 recoded the categories primary, some secondary into one group because of small numbers in each group: 1=primary/some secondary; 2=completed secondary; 3=some additional training; 4=completed undergraduate university; 5=completed postgraduate university 1=18–29yrs, 2=30–44yrs, 3=45+yrs 1=18–24yrs, 2=25–32yrs, 3=33–40yrs, 4=41–49yrs, 5=50+yrs 0905-section3.QX5 7/12/04 4:12 PM Page 305 Appendix Details of data files Copy of the questionnaire used in survey.sav On the pages that follow, I have included a portion of the actual questionnaire used to collect the data included in the survey.sav file The first page includes the demographic questions, followed by the Life Orientation Test (6 items) and the Positive and Negative Affect Scale (20 items) Full reference details of each scale included in the questionnaire are provided in the list given earlier in this appendix Sample questionnaire ❒ male (please tick whichever applies) ❒ female Age: _ (in years) What is your marital status? (please tick whichever applies) ❒ single ❒ in a steady relationship ❒ living with partner ❒ married for first time ❒ remarried ❒ separated ❒ divorced ❒ widowed Do you have any children currently living at home with you? ❒ yes (please tick) ❒ no What is the highest level of education that you have completed? (please tick the highest level you have completed) ❒ primary school ❒ some secondary school ❒ completed secondary school ❒ some additional training (apprenticeship, trade courses) ❒ undergraduate university ❒ postgraduate university What are the major sources of stress in your life? _ Do you smoke? ❒ yes (please tick) ❒ no If yes, how many cigarettes you smoke per week? Sex: 305 0905-section3.QX5 306 7/12/04 4:12 PM Page 306 SPSS Survival Manual Please read through the following statements and decide how much you either agree or disagree with each Using the scale provided write the number that best indicates how you feel on the line next to each statement strongly disagree strongly agree _ In uncertain times I usually expect the best _ If something can go wrong for me it will _ I’m always optimistic about my future _ I hardly ever expect things to go my way _ Overall I expect more good things to happen to me than bad _ I rarely count on good things happening to me Source: Scheier, Carver & Bridges, 1994 This scale consists of a number of words that describe different feelings and emotions For each item indicate to what extent you have felt this way during the past few weeks Write a number from to on the line next to each item very slightly or not at all a little moderately quite a bit extremely _ interested _ upset _ scared _ proud _ ashamed _ determined _ active Source: Watson, Clark & Tellegen, 1988 _ distressed _ strong 10 _ hostile 11 _ irritable 12 _ inspired 13 _ attentive 14 _ afraid 15 _ excited 16 _ guilty 17 _ enthusiastic 18 _ alert 19 _ nervous 20 _ jittery 0905-section3.QX5 7/12/04 4:12 PM Page 307 Appendix Details of data files Part B: Materials for experim.sav Codebook for experim.sav Full variable name SPSS variable name SPSS variable label Coding instructions Id id id Identification number sex sex sex 1=males, 2=females Age age age in years Group group type of class 1=maths skills, 2=confidence building Fear of Statistics test at Time fost1 fear of stats time1 Fear of Statistics test score at Time Possible range 20–60 High scores indicate high levels of fear Confidence in Coping with Statistics Time1 conf1 confidence time1 Confidence in Coping with Statistics Test score at Time Possible range 10–40 High scores indicate higher levels of confidence Depression Time depress1 depression time1 Depression scale scores at Time Possible range 20–60 High scores indicate high levels of depression Fear of Statistics test at Time fost2 fear of stats time2 Fear of Statistics test score at Time Possible range 20–60 High scores indicate high levels of fear Confidence in Coping with Statistics Time2 confid2 confidence time2 Confidence in Coping with Statistics test score at Time Possible range 10–40 High scores indicate high levels of confidence Depression Time depress2 depression time2 Depression scale scores at Time Possible range 20–60 High scores indicate high levels of depression Fear of Statistics test at Time fost3 fear of stats time3 Fear of Statistics test score at Time Possible range 20–60 High scores indicate high levels of fear Confidence in Coping with Statistics Time3 conf3 confidence time3 Confidence in Coping with Statistics test score at Time Possible range 10–40 High scores indicate high levels of confidence Depression Time depress3 depression time3 Depression scale scores at Time Possible range 20–60 High scores indicate high levels of depression Statistics Exam scores exam exam Scores on the statistics exam Possible range 0–100 307 0905-section3.QX5 308 7/12/04 4:12 PM Page 308 SPSS Survival Manual Part C: Materials for staffsurvey.sav Staff survey (selected items) Age: ❒ under 20 ❒ 21 to 30 ❒ 31 to 40 ❒ 41 to 50 ❒ over 50 yrs Length of service with the organisation (in years): Employment status: ❒ permanent ❒ casual For each of the aspects shown below please rate your level of agreement and importance using the following scales: Agreement: 1=not at all, 2=slight extent, 3=moderate extent, 4=great extent, 5=very great extent Importance: 1=not at all, 2=slightly important, 3=moderately important, 4=very important, 5=extremely important Agreement Is it clear what is expected of you at work? At work have you been provided with all the equipment and materials required for you to your work efficiently? Does the organisation keep you up to date with information concerning development and changes? Do you receive recognition from the organisation for doing good work? Does your manager or supervisor encourage your development at work? Do you feel that your opinions seem to count to the organisation? Does the organisation make you feel that your job is important? Do you feel that your fellow workers are committed to doing good quality work? Has your performance been assessed or discussed in the last six months? 10 Have you had the opportunity over the last year at work to improve your skills? Importance 12345 12345 12345 12345 12345 12345 12345 12345 12345 12345 12345 12345 12345 12345 12345 12345 12345 12345 12345 12345 Would you recommend this organisation as a good place to work? ❒ Yes ❒ No 0905-section3.QX5 7/12/04 4:12 PM Page 309 Appendix Details of data files Codebook for staffsurvey.sav Description of variable SPSS variable name Identification number id City of residence of staff member City Age of staff member age Years of service with the organisation Employment status Q1 level of agreement service Q1 level of importance Q1imp Q2 level of agreement Q2a Q2 level of importance Q2imp Q3 level of agreement Q3a Q3 level of importance Q3imp Q4 level of agreement Q4a Q4 level of importance Q4imp Q5 level of agreement Q5a Q5 level of importance Q5imp Q6 level of agreement Q6a Q6 level of importance Q6imp Q7 level of agreement Q7a employstatus Q1a Coding instructions Subject identification number Each city was given a numerical code 1=under 20, 2=21 to 30, 3=31 to 40, 4=41 to 50, 5=over 50 Years of service (if less than record as decimal: e.g 6mths=.5 year) 1=permanent, 2=casual 1=not at all, 2=to a slight extent, 3=to a moderate extent, 4=to a great extent, 5=to a very great extent 1=not important, 2=slightly important, 3=moderately important, 4=very important, 5=extremely important 1=not at all, 2=to a slight extent, 3=to a moderate extent, 4=to a great extent, 5=to a very great extent 1=not important, 2=slightly important, 3=moderately important, 4=very important, 5=extremely important 1=not at all, 2=to a slight extent, 3=to a moderate extent, 4=to a great extent, 5=to a very great extent 1=not important, 2=slightly important, 3=moderately important, 4=very important, 5=extremely important 1=not at all, 2=to a slight extent, 3=to a moderate extent, 4=to a great extent, 5=to a very great extent 1=not important, 2=slightly important, 3=moderately important, 4=very important, 5=extremely important 1=not at all, 2=to a slight extent, 3=to a moderate extent, 4=to a great extent, 5=to a very great extent 1=not important, 2=slightly important, 3=moderately important, 4=very important, 5=extremely important 1=not at all, 2=to a slight extent, 3=to a moderate extent, 4=to a great extent, 5=to a very great extent 1=not important, 2=slightly important, 3=moderately important, 4=very important, 5=extremely important 1=not at all, 2=to a slight extent, 3=to a moderate extent, 4=to a great extent, 5=to a very great extent 309 0905-section3.QX5 310 7/12/04 4:12 PM Page 310 SPSS Survival Manual Description of variable SPSS variable name Coding instructions Q7 level of importance Q7imp Q8 level of agreement Q8a Q8 level of importance Q8imp Q9 level of agreement Q9a Q9 level of importance Q9imp Q10 level of agreement Q10a Q10 level of importance Q10imp Recommendation recommend 1=not important, 2=slightly important, 3=moderately important, 4=very important, 5=extremely important 1=not at all, 2=to a slight extent, 3=to a moderate extent, 4=to a great extent, 5=to a very great extent 1=not important, 2=slightly important, 3=moderately important, 4=very important, 5=extremely important 1=not at all, 2=to a slight extent, 3=to a moderate extent, 4=to a great extent, 5=to a very great extent 1=not important, 2=slightly important, 3=moderately important, 4=very important, 5=extremely important 1=not at all, 2=to a slight extent, 3=to a moderate extent, 4=to a great extent, 5=to a very great extent 1=not important, 2=slightly important, 3=moderately important, 4=very important, 5=extremely important 0=no, 1=yes Calculated variables Total Staff Satisfaction Scale Length of service (3 groups) Log transformation of service Age recoded in gps totsatis Servicegp3 logservice agerecode High scores indicate greater satisfaction 1=< or = to 2yrs, 2=3 to 5yrs, 3=6+ yrs 1=18 to 30yrs, 2=31 to 40 yrs, 3=41 to 50yrs, 4=50+ 0905-section3.QX5 7/12/04 4:12 PM Page 311 Appendix Details of data files Part D: Materials for sleep.sav Codebook for sleep.sav Description of variable SPSS variable name Coding instructions Identification Number id Sex sex 0=female, 1=male Age age in years Marital status marital 1=single, 2=married/defacto, 3=divorced, 4=widowed Highest education level achieved edlevel 1=primary, 2=secondary, 3=trade, 4=undergrad, 5=postgrad Weight (kg) weight in kg Height (cm) height in cm Rate general health healthrate 1=very poor, 10=very good Rate physical fitness fitrate 1=very poor, 10=very good Rate current weight weightrate 1=very underweight, 10=very overweight Do you smoke? smoke 1=yes, 2=no How many cigarettes per day? smokenum Cigs per day How many alcoholic drinks per day? alchohol Drinks per day How many caffeine drinks per day? caffeine Drinks per day Hours sleep/weeknights hourwnit Hrs sleep on average each weeknight Hours sleep/weekends hourwend Hrs sleep on average each weekend night How many hours sleep needed? hourneed Hrs of sleep needed to not feel sleepy Trouble falling asleep? trubslep 1=yes, 2=no Trouble staying asleep? trubstay 1=yes, 2=no Wake up during night? wakenite 1=yes, 2=no Work night shift? niteshft 1=yes, 2=no Light sleeper? liteslp 1=yes, 2=no Wake up feeling refreshed weekdays? refreshd 1=yes, 2=no Satisfaction with amount of sleep? satsleep 1=very dissatisfied, 10=to a great extent Rate quality of sleep qualslp 1=very poor, 2=poor, 3=fair 4=good, 5=very good, 6=excellent Rating of stress over last month stressmo 1=not at all, 10=extremely Medication to help you sleep? medhelp 1=yes, 2=no Do you have a problem with your sleep? problem 1=yes, 2=no 311 0905-section3.QX5 312 7/12/04 4:12 PM Page 312 SPSS Survival Manual Description of variable SPSS variable name Coding instructions Rate impact of sleep problem on mood impact1 1=not at all, 10=to a great extent Rate impact of sleep problem on energy level impact2 1=not at all, 10=to a great extent Rate impact of sleep problem on concentration impact3 1=not at all, 10=to a great extent Rate impact of sleep problem on memory impact4 1=not at all, 10=to a great extent Rate impact of sleep problem on life sat impact5 1=not at all, 10=to a great extent Rate impact of sleep problem on overall wellbeing impact6 1=not at all, 10=to a great extent Rate impact of sleep problem on relationships impact7 1=not at all, 10=to a great extent Stop breathing during your sleep? stopb 1=yes, 2=no Restless sleeper? restlss 1=yes, 2=no Ever fallen asleep while driving? drvsleep 1=yes, 2=no Epworth sleepiness scale ess Total ESS score (range from 0=low to 24=high daytime sleepiness) HADS Anxiety anxiety Total HADS Anxiety score (range from 0=no anxiety to 21=severe anxiety) HADS Depression depress Total HADS Depression score (range from 0=no depression to 21=severe depression) Rate level of fatigue over last week fatigue 1=not at all, 10=to a great extent Rate level of lethargy over last week lethargy 1=not at all, 10=to a great extent Rate how tired over last week tired 1=not at all, 10=to a great extent Rate how sleepy over last week sleepy 1=not at all, 10=to a great extent Rate lack energy over the last week energy 1=not at all, 10=to a great extent Problem staying asleep recoded stayslprec 0=no, 1=yes Problem getting to sleep recoded getsleprec 0=no, 1=yes Quality of sleep recoded into groups qualsleeprec 1=very poor, poor; 2=fair; 3=good; 4=very good, excellent Sleepiness and Associated Sensations scale totsas Total Sleepiness and Associated Sensation Scale score (5=low, 50=extreme sleepiness) Number of cigs per day recoded into groups cigsgp3 1=