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Explore the scientific methodology in psychology, types of measurement scales, study strategies, and designs, ranging from observational to randomized experiments. Learn about different statistical selections and factors influencing research.
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1. INTRODUCTION TO RESEARCH PROCEDURES Design and Data Analysis in Psychology II Susana Sanduvete Chaves SalvadorChacón Moscoso
PSYCHOLOGY AS A SCIENCE • Psychology - scientific study of behavior and mental processes • Goals of Psychology • describe behavior • explain behavior • predict behavior • control “some” behavior
SCIENTIFIC METHODOLOGY IN PSYCHOLOGY • Problem definition: hypothesis (defined empirically). • Method. • Data analysis. • Discussion and conclusions.
TYPES OF MEASUREMENT SCALES Numbers can be used in a variety of ways: • Identification (as labels); example: countries. • Order (to indicate ‘more or less’ than); example: level of agreement. • Equal intervals (to indicate exact relationships); example: 500-300 = 900-700. • Absolute zero (0 has an absolute meaning); example: money - $0 means NO money Each of these specifies a different scale of measurement.
TYPES OF MEASUREMENT SCALES II Nominal scale - sorts objects into categories Ordinal scale - ranks objects/events by magnitude Interval scale - intervals between adjacent values are equal Ratio scale - all of above AND a meaningful zero point
TYPES OF STUDY STRATEGY • Cross-sectional studies (transversal): each person only can be measured for one independent variable value. • Repeated measures studies (longitudinal): each person can be measured for each independent variable value. • Mixed: There is at least one transversal and one longitudinal variable.
STUDIES TAXONOMY DEPENDING ON THE NUMBER OF VARIABLES • Depending on the number of dependent variables: • 1: univariate. • >1: multivariate . • Depending on the number of independent variables: • 1: univariable: • 2 values: biconditional. • >2 values: multiconditional. • >1 variable: multivariable or factorial (example: two variables and two conditions, 2x2).
TYPES OF DESIGNS From low to high control: Observational study Survey study Quasi-experimentRandomized experiment (low intervention) (medium intervention) (high intervention) There is no IV There is no IV There is IV There is IV Natural behavior Elicited behavior Non-randomized Randomized assignment assignment
TYPES OF DESIGN II • Randomized experiment (R.E.) is a study in which an intervention is deliberately introduced to observe its effects, and in which units are assigned to conditions randomly (Shadish, Cook and Campbell, 2002). • A quasi-experiment (Q-E) is a study in which an intervention is deliberately introduced to observe its effects, but in which units are not assigned to conditions randomly (Shadish, Cook and Campbell, 2002). • Survey study (S.S.) records the occurrence of elicited behaviors (questionnaires, interviews) [Post hoc studies] • An observational study (O.S.) observes the occurrence of behavior, allowing it to be formally recorded and quantified, but without manipulating it (Anguera, 2008).
TYPES OF DESIGN III • R.E. might be called high intervention studies (researchers have a high control over the situation, and provoke behaviors). • Q-E might be called medium intervention studies (researchers have certain degree of control over the situation, without being able to randomly assign subjects to conditions, and can provoke a change in subjects' behaviors because of the manipulation of the variables). • O.S. might be called low intervention studies (observers do not have any control over the situation and they just observe behaviors that appear depending on subjects’ desire). • The distinction between low, medium, and high intervention studies is merely one of convenience, as some quasi-experiments can have high control over assignment to the intervention. • The distinction becomes a matter of degree rather than a matter being absolute.
TYPES OF DESIGN IV • More information in: Chacón, S., Sanduvete, S., Portell, M. & Anguera, M. T. (2013). Reporting a program evaluation: Needs, program plan, intervention, and decisions. International Journal of Clinical and Health Psychology, 13(1), 58-66. [2011 impact factor: 2.787; Q1: posición 21 de 109 en categoría Psychology-Clinical]. Available in http://apps.elsevier.es/watermark/ctl_servlet?_f=10&pident_articulo=90184976&pident_usuario=0&pcontactid=&pident_revista=355&ty=89&accion=L&origen=zonadelectura&web=http://zl.elsevier.es&lan=en&fichero=355v13n01a90184976pdf001.pdf
Statisticselectiondependingonpreviousfactors http://www.ats.ucla.edu/stat/spss/whatstat/