47.269: Research I: The Basics Dr. Leonard Spring 2010
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1 47.269: Research I: The Basics Dr. Leonard Spring 2010 Basic Approaches to Empirical Research: Experimental vs. Non-experimental47.269: Research I: The BasicsDr. LeonardSpring 2010
2 Beginning the research design Empirical means based on systematic observation, or data collectionInvolves determining who or what to study and how or when to studyImportant to also explain why one wants to study a phenomenon (literature review -> theory -> hypothesis)Can be quantitative or qualitative √Can be experimental or non-experimentalCan be basic or applied researchCan be laboratory or field settingBasic research: The goal is to increase understanding about a phenomena for the sake of gaining knowledge.Applied research: The goal is to increase understanding of and find solutions to “real world” problems through research.
3 Beginnings of empiricism in psychology Woodworth’s (1938) Experimental Psychology, a.k.a. the “Columbia bible”Described accumulation of laboratory and experimental methods from beginning of the field of psychology when Wundt began conducting his “atoms of the mind” experimentsFocused on experiments related to the parts of psychology we now refer to as cognition, sensation, and perceptionClarified the distinction between experimental and non-experimental/correlational research we use todayFirst to use the terms independent variable and dependent variable as we use them todayWoodworth was trying to legitimize the science of psychologyProfessor at ColumbiaResearch on sensation, perception, and intelligence – famous World Fair study in St. Louis – warned of inaccuracy of group averages in comparing intelligence of different races!One of the early APA presidentsWrote a lot about research methods
4 I.V. and D.V.Independent variable is be manipulated or varied systematically while dependent variable can only be observed or measuredIndependent variable is sometimes also called the predictor variable because it is used to predict some outcome in behaviorDependent variable is sometimes also called the criterion variable because it is thought of s a standard being assessedE.g., SAT scores used to predict college GPAPg. 11 in your text GPA is often the criterion by which SAT scores are judged to be valid.Does anyone know how good of a predictor SAT scores are? How could we explaint his relationship?
5 Two major research designs Experimental Design: Any scientific study in which the researcher systematically varies one or more variables, holding all others constant, to see if another variable is affectedIn other words, does X cause changes in Y?Non-experimental DesignCorrelational Method: Any scientific study in which the researcher observes or measures (without manipulating) two or more variables to find relationshipsIn other words, are x and y associated?
6 Two major research designs Key difference is degree of control of situation and means of data collection, or measurementExperimental designs have more controlExperimental tends to collect data by measuring some concrete observation or effect after treatmentNon-experimental tends to collect data by observation or self-report (surveys)BUT both often use same measuresBoth could employ a quantitative or qualitative approach (majority of both are quantative!)Both could be basic (for the sake of knowledge) or applied (seeking practical applications) researchBoth could take place in a laboratory or field setting, though experimental is more often in laboratoryBOTH COULD USE SAME KINDS OF MEASUREMENT!
7 Pros and Cons?Experimental designs can control effects of extraneous (outside) variables (+)Experimental designs may produce artificial results or involve placebo effects (-)Experimental designs require two variables that occur together or two comparable groupsNon-experimental designs are subject to the influence of extraneous variables (-)Correlations might involve unseen “third variables”, indicating a spurious relationship, or directionality problemsNon-experimental designs can be used for prediction of future events (+)Non-experimental designs can study a greater variety of variables (+)
8 Variations in Experimental designs Treatment given to observe effects (causal)If impossible to conduct experiment, may try a causal-comparative study (search for causes of already existing phenomena -- more non-experimental)When might experimentation be impossible?Independent variable must have two or more levels for comparisonOften accomplished by having experimental group(s) and control group (no treatment)True experiment if assignment of participants to groups is randomImpossible for ethical or practical reasons…amount of cigarettes lung cancer example
9 Variations in Non-experimental designs Goal is to capture attitudes and behaviors as they naturally occurCan rely on researcher to observe participants or can ask participants to provide their own description (i.e., survey or interview)Variables can be categorical (nominal, ordinal) or quantitative (interval, ratio)Categories must be mutually exclusive and exhaustive so that all possible responses are accounted forE.g., gender and voting preference; male-female are mutually exclusive, all candidates names plus an option for undecided would be exhaustive
10 Third option: Quasi-experimental designs Occur more commonly in psychologyApply experimental principles like cause and effect or group comparison to field, or less controlled settingsLess control over extraneous variables but can take place outside of lab, which may decrease the artificial feelingInterpretation of results not as clean as in experimental research but closer to “real world” application
11 In-class activityWorking in groups, design an experimental study and a non-experimental study for the topic you have been givenConsider if each approach would be… quantitative or qualitativebasic or applied researchlaboratory or field settingMake sure to explain specifically how data would be collected and for what duration