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PSYC 217 (69)
Chapter 4

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PSYC 217
Rebecca Todd

Chapter 42014916246Studying Behaviour Variables Any even situation behaviour or individual characteristics that can take more than one value IT VARIESFour general types of variablesSituational variable Describes characteristics of a situation or environment Ex The length of words you read in a book the number of people who are squeezed into a classroomResponse variable the responses or behaviours of individualsEx Reaction time performance on a cognitive task Participant variable the characteristics of individuals that they bring with them tostudy Ex Sex intelligence and personality traits Mediating variable A psychological process that occurs between a situational variable anda particular behaviour response that helps to explain the relationship between them Operational Definitions of Variables Operational definition definition of a concept that specifies the operation used to measure or manipulate the concept Variables must be operationally defined so that they can be studied empirically Value of variable numeric valueEx Distance between people standing next to each otherLevel of variable Different categories Ex Ethnicity Nonexperimental and Experimental Methods Overview Two general approaches to the study of relationships among variablesNonexperimental method relationships are studied by observing or otherwise measuring the variables of interest Ex Directly observing behaviour recording physiological responses Experimental method Direct manipulation and control of variables The researcher manipulates the first variable of interest and then observes the response One variable is introduced first to see whether it affects the second variable Nonexperimental MethodAllows us to observe covariation between variablesRelationships Between Variables Four most common relationshipsPositive linear relationship Increases in the values of one variable are accompanied by increases in the values of the second variable Negative Linear relationship Increases in the values of one variable are accompanied by decreases in the values of the other variable Curvilinear relationship increases in the values of one variable are accompanied by both increases and decreases in the values of the other variable The direction of the relationship changes at least once No relationship When there is no relationship between the two variables the graph is simply a flat line Keep in mind that these are basic clearest examples almost any shape can describe the relationship between two variables The strength of the relationshipCorrelation coefficient the strength of relationship between variablesRelationships and Reduction of Uncertainty When we detect a relationship between variables we reduce uncertainty about the world by increasing our understanding of the variables we are examining Uncertainty there is randomness in events Random variability error variance The relationships between variables are rarely perfect Interpreting Nonexperimental Results CautionWeak if we ask questions about cause and effect It can be difficult to determine the direction of cause and effectThe thirdvariable problemthat is extraneous variables may be causing an observed relationship Direction of Cause and Effect The causal pattern may operate in both direction The Third Variable Problem When the nonexperimental method is used there is the danger that the two variables measured are not directly related to each other The third variable is any variable that is extraneous to the two variables being studied Experimental Method When researches use the experimental method to investigate the relationship between variables the variables are conceptualized as having a causeandeffect connection Independent variable The variable that is manipulated to observe its effect on the depend variable Dependent variable The variable that is the participants response to and dependent on the level of the manipulated independent variable Why do Experiments enable cause and effect influences One variable is manipulated and then the other is measured It attempts to eliminate the influence of all variables except the one that is being manipulated Experiment control Treating participants in all groups in the experiment identically The only difference between the groups is the independent variable Confounding variable A variable that is intertwined with another variable so you cannot determine which of the variables is operating Third variables cause the relationship between two other variables whereas confounding variables are intertwined with another variable in your study so that you cannot tell which is at work Random Assignment to Condition Random assignments Controlling for the effects of extraneous variables by ensuring that participants in an experiment are assigned to condition in a manner determined entirely by chanceCausality and Internal Validity Internal Validity the ability to draw accurate conclusions about causal relationships from our data Choosing a Method Advantage of Multiple Methods
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