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” beha vior

SCIENTIFIC METHODOLOGY IN PSYCHOLOGY 1.Problem definition: hypothesis (defined empirically). 2.Method. 3.Data analysis. 4.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: = 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

ScalePropertiesExamples Nominal identity countries, colors, gender Ordinal identity, magnitude class standing, sports standings, results of races Interval identity, magnitude, equal intervals temperature (F or C), scores on intelligence tests Ratio identity, magnitude, equal intervals, absolute zero point length, weight, time, reaction time, number of responses made by a subject TYPES OF MEASUREMENT SCALES III

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.

8 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).

9 TYPES OF DESIGNS From low to high control: Observational study Survey study Quasi-experiment Randomized 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), [2011 impact factor: 2.787; Q1: posición 21 de 109 en categoría Psychology- Clinical]. Available in articulo= &pident_usuario=0&pcontactid=&pident_r evista=355&ty=89&accion=L&origen=zonadelectura&web=htt p://zl.elsevier.es&lan=en&fichero=355v13n01a pdf0 01.pdf

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