2011-Psych 60-Lecture 3

2011-Psych 60-Lecture 3 - 4/1/11 Announcements Enrollment...

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Unformatted text preview: 4/1/11 Announcements Enrollment limits have been increased Today Philosophy of Science Research Methods in Psychology 1 4/1/11 Epistemology A branch of philosophy concerned with the nature and acquisiCon of knowledge Science vs. Pseudoscience 2 4/1/11 Science vs. Pseudoscience The Problem of Demarca/on Sir Karl Popper 1902 - 1994 The Criterion of Falsifiability The perspecCve that for a hypothesis or theory to be regarded as scienCfic, it must be falsifiable (refutable) on the basis of some physical observaCon A necessary but not sufficient criterion of scienCfic knowledge 3 4/1/11 Empiricism The perspecCve that knowledge and evidence must be empirical, or empirically based: dependent on that which can be physically observed Psychological theories can be refuted by observaCon Psychological science is methodologically empirical Research Methods in Psychology 4 4/1/11 Empirical Research Methodologies Empirical Research Methodologies CorrelaConal Method Experimental Method CorrelaConal Method Experimental Method CorrelaConal Method Two or more variables are observed to determine if there is a rela/onship between them 5 4/1/11 Murders Ice Cream Sales Spurious CorrelaCon When an observed mathemaCcal relaConship between two variables is due to some unseen, unmeasured or unknown third variable SomeCmes referred to as a confounding 6 4/1/11 7 4/1/11 Causality and the CorrelaConal Method "Cum hoc ergo propter hoc" "CorrelaCon does not imply causaCon" Empirical Research Methodologies CorrelaConal Method Experimental Method Empirical Research Methodologies CharacterisCcs of a True Experiment CorrelaConal Method Experimental Method 8 4/1/11 CharacterisCcs of a True Experiment ManipulaCon: the experimenter has manipulated some independent variable to see the effect it has on the dependent variable Independent Variable In an experiment, the independent variable (IV) is what is manipulated or changed by the experimenter "Levels" of the IV refers to the different types of treatments or condi/ons (e.g. caffeine or no caffeine before an exam) Dependent Variable In an experiment, the dependent variable (DV) is what is measured CharacterisCcs of a True Experiment ManipulaCon: the experimenter has manipulated some independent variable to see the effect it has on the dependent variable 9 4/1/11 CharacterisCcs of a True Experiment ManipulaCon: the experimenter has manipulated some independent variable to see the effect it has on the dependent variable Control: extraneous variables are held constant across the levels of the independent variable Extraneous Variable Variables that have some relaConship to the dependent variable but are not of direct interest in the experiment CharacterisCcs of a True Experiment ManipulaCon: the experimenter has manipulated some independent variable to see the effect it has on the dependent variable Control: extraneous variables are held constant across the levels of the independent variable CharacterisCcs of a True Experiment ManipulaCon: the experimenter has manipulated some independent variable to see the effect it has on the dependent variable Control: extraneous variables are held constant across the levels of the independent variable Random Assignment: chance alone dictates what treatment each individual receives 10 4/1/11 Random Assignment The process of assigning treatments (levels of the IV) to subjects so that only chance is responsible for which treatment each subject receives Ensures that there are no systema/c differences across groups before treatment (groups will only differ due to chance) FR OM FO BE RE PopulaCon 260- Psych 60 students PopulaCon Parameters Average Age: 19.8 Average IQ: 110.5 70% Female, 30% Male Sample 2 Jake Laura Tiffany Sarah Ann Sample 1 Mike Tom Jennifer Andy Lucy Sample 1 Sta/s/cs Average Age: 21.8 Average IQ: 106.2 40% Female, 60% Male Sample 2 Sta/s/cs Average Age: 19.2 Average IQ: 112.2 80% Female, 20% Male FR BE OM FO RE Sampling Error The discrepancy (or amount of error) that exists between a sample staCsCc and the corresponding populaCon parameter Random Assignment The process of assigning treatments (levels of the IV) to subjects so that only chance is responsible for which treatment each subject receives Ensures that there are no systema/c differences across groups before treatment (groups will only differ due to chance) 11 4/1/11 CharacterisCcs of a True Experiment ManipulaCon: the experimenter has manipulated some independent variable to see the effect it has on the dependent variable Control: extraneous variables are held constant across the levels of the independent variable Random Assignment: chance alone dictates what treatment each individual receives CharacterisCcs of a True Experiment Can Provide Evidence of Causality 12 4/1/11 Jon Tristan F-18 "Hornet" F-22 "Raptor" 13 4/1/11 Jon's CorrelaConal Study Hanger Sample 1 n = 50 Access Logs Record Top Speed Record Top Speed = 1,327 miles/hour Sample 2 n = 50 Access Logs = 1,683 miles/hour Jon's CorrelaConal Study Confounding Variable An extraneous variable that correlates with both the dependent variable and the independent variable. Sample 1 n = 50 Access Logs Hanger Record Top Speed Record Top Speed Sample 2 n = 50 Access Logs 14 4/1/11 Tristan's True Experiment Randomly Assign Manipulate Independent Variable Measure Dependent Variable = 1,327 miles/hour Hanger Sample 1 n = 50 Run Test in Tunnel Measure Top Speed Measure Top Speed = 1,683 miles/hour Sample 2 n = 50 Run Test in Tunnel Control Extraneous Variables Tristan's True Experiment Randomly Assign Manipulate Independent Variable Measure Dependent Variable = 1,327 miles/hour Hanger Sample 1 n = 50 Run Test in Tunnel Measure Top Speed Measure Top Speed = 1,683 miles/hour Sample 2 n = 50 Run Test in Tunnel Control Extraneous Variables 15 4/1/11 Tristan's True Experiment Randomly Assign Manipulate Independent Variable Measure Dependent Variable CharacterisCcs of a True Experiment ManipulaCon: the experimenter has manipulated some independent variable to see the effect it has on the dependent variable Control: extraneous variables are held constant across the levels of the independent variable Random Assignment: chance alone dictates what treatment each individual receives Hanger Sample 1 n = 50 Run Test in Tunnel Measure Top Speed Measure Top Speed Sample 2 n = 50 Run Test in Tunnel Control Extraneous Variables For Next Time Read Syllabus (if you haven't already) Chapter 2 Do Buy Clicker (parCcipaCon points start Monday) Buy Book Homework 1 (due Monday before start of class) 16 ...
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