Statistics Without Maths for Psychology

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Cry Conduct t-test analyses of the single DVs Conduct X2 analyses of the DVs followed by t-tests None of the above More definitions explain the key terms you need to understand statistics Up-to-date examples from the literature keep you informed of current research NEW interviews with researchers bring statistics to life NEW full-colour design makes it even easier to follow the steps in SPSS NEW SPSS exercises allow you to learn by using the software Full guidance on using version 18 of SPSS, as well as earlier versions of the software 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. inferences, Journal of Speech, Language and Hearing Research, 52, 359–72 (Blake, M.L. 2009), Reprinted with permission from Inferencing processes after right hemisphere brain damage: Maintenance of inferences by M.L. Blake. Journal of Speech, Language and Hearing Research, 53, 359–72. Copyright 2009 by American Speech-Language-Hearing Association. All Rights Reserved; Table on page 229 from Counting on working memory when learning to count and to add: a pre-school study, Developmental Psychology, 45 (6), 1630–1643 (Noel, M-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 256 from Method of delivery and subjective distress: women’s emotional responses to childbirth practices, Journal of Reproductive and Infant Psychology, 18 (2), 153–62 (Maclean, L.I., McDermott, M.R. and May, C.P. 2000), © Society for Reproductive and Infant Psychology reprinted by permission of (Taylor & Francis Ltd, http://www.tandf.co.uk/journals) on behalf of Society for Reproductive and Infant Psychology; Table on page 287 from Efficacy of a Camp-Based Intervention for Childhood Traumatic Grief, Research on Social Work Practice, 19, 19–30 (McClatchey, I.S., Vonk, M.E. and Palardy, G. 2009), Reprinted by permission of SAGE Publications; Tables on page 311 from The effects of cigarette smoking and abstinence on auditory verbal learning, Human Psychopharmacology: Clinical and Experimental, 23, 621–627 (Soar, K., Dawkins, L., Begum, H. and Parrott, A.C. 2008); Table on page 312 from Differential effects of age on involuntary and voluntary autobiographical memory, Psychology and Aging, 24 (2), 397–411 (Schlagman, S., Kliegel, M., Schulz, J. and Kvavilashvili, L. 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/a0015785. No further reproduction or distribution is permitted without written permission from the American Psychological Association; Table on page 416 from Barriers to engagement in sleep restriction and stimulus control in chronic insomnia, Journal of Consulting and Clinical Psychology, 76 (5), 820–828 (Vincent, N., Lewycky, S. and Finnegan, H. 2008), Copyright © 2009 by the American Psychological Association. Reproduced with permission. The official citation that should be used in referencing this material is doi:10.1037/0022-006X.76.5.820. No further reproduction or distribution is permitted without written permission from the American Psychological Association; Table on page 447 from An evaluation study of the young empowered sisters (YES!) program: promoting cultural assets among African American adolescent girls through a culturally relevant school-based intervention, Journal of Black Psychology, 34, 281–308 (Thomas, O., Davidson, W. and McAdoo, H. 2008), Reprinted by permission of SAGE Publications; Table on page 475 from Developing a measure of sluggish cognitive tempo for children: content validity, factor structure, and reliability, Psychological Assessment, 21 (3), 380–9 (Penny, A.M., Waschbusch, D.A., Klein, R.M., Corkum, P. and Eskes, G. 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/a0016600. No further reproduction or distribution is permitted without written permission from the American Psychological Association; Table on pages 477–8 from Selectivity of executive function deficits in mild cognitive impairment, Neuropsychology, 23 (5), 607–18 (Brandt, J., Aretouli, E., Neijstrom, E., Bandeen-Roche, K., Samek, J., Manning, K. & Albert, M.S. 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/a0015851. No further reproduction or distribution is permitted without written permission from the American Psychological Association; Table on page 532 from Faith in intuition is associated with decreased latent inhibition in a sample of high-achieving adolescents, Psychology of Aesthetics, Creativity and the Arts, 3 (1), 28–34 (Kaufman, S., B. 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/a0014822. No further reproduction or distribution is permitted without written permission from the American Psychological Association; Table on page 533 from The Association Between the Negative 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’.

Definition Exploratory data analyses are where we explore the data that we have collected in order to describe it in more detail. These techniques simply describe our data and do not try to draw conclusions about any underlying populations. The purpose of linear regression SPSS: drawing the line of best fit SPSS: linear regression analysis Multiple regression study, so you need to obtain far more participants than you think you need, to make sure you have enough participants in each cell. X2 is always positive (because a squared number is always positive). Whereas DF roughly equates to the number of participants in most statistical analyses, it does not in X2, as DF is calculated by number of rows minus 1 (r " 1) multiplied by number of columns minus 1 (c " 1). In this case, you can see that a 2 ¨ 2 X2 will always have DF 2 1 because (r " 1) 2 (c " 1) 2 (2 " 1) 2 (2 " 1) 2 1.

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test of independence: r ¬ c What if you have more than two levels? It is perfectly possible to have more rows and columns. We still have two categorical variables, but this time we have more categories to choose from. X2 can handle this quite easily. Let’s assume, staying with our smoke/drink example, that we have three levels of smoke: heavy smokers, light smokers and non-smokers. We could also have heavy drinkers, light drinkers and teetotallers (see Table 9.8). This is a 3 ¨ 3 contingency table, for obvious reasons. The calculations are worked out in exactly the same way as we have described for the 2 ¨ 2 table. The degrees of freedom, however, will be different. Remember: DF 2 (c " 1) ¨ (r " 1) So: 2 ¨ 2 2 4 Another way of applying probabilities to research: hypothesis testing Null hypothesis Logic of null hypothesis testing The significance level Statistical significance Gain a thorough understanding of introductory statistics, data analysis & application of statistical concepts Answers to activities and SPSS exercises Appendix 1: Table of z-scores and the proportion of the standard normal distribution falling above and below each score Appendix 2: Table r to zr

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 Coach

Supporting resources Visit www.pearsoned.co.uk/dancey to find valuable online resources Companion Website for students: ■ Multiple choice questions for each chapter to test your understanding ■ SPSS datasets for each chapter ■ Extra datasets and exercises ■ An interactive flowchart to help you choose your method of analysis ■ A list of where to find core content in the book outlined by the British Psychological Society ■ Links to useful resources on the web ■ A handy guide to report writing For instructors: ■ A testbank of at least 20 questions per chapter ■ Downloadable PowerPoint slides of all the figures from the book Also – The Companion Website provides the following features: ■ A Syllabus and Profile Manager ■ Online help and search functions ■ Email results functions For more information please contact your local Pearson Education sales representative or visit www.pearsoned.co.uk/dancey