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Correlational Research Inferential/Descriptive Statistic (r) Describes strength of linear relation between two variables Strength of relation = degree.

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Presentation on theme: "Correlational Research Inferential/Descriptive Statistic (r) Describes strength of linear relation between two variables Strength of relation = degree."— Presentation transcript:

1 Correlational Research Inferential/Descriptive Statistic (r) Describes strength of linear relation between two variables Strength of relation = degree of association Does knowing an individual’s score on A tell you much about that individual’s score on B? How much does it tell you? Some properties of r Ranges between -1 and 1 inclusive Sign (+ or -) gives direction of relation Absolute value gives strength r 2 gives proportion of variance accounted for

2 Correlations Correlation between VIQ and PIQ = +.53 Characterized as strong and positive

3 Correlations Correlation between C and Behavioral Impulsivity = -.41 Characterized as moderate-strong and negative

4 Correlations Correlation between C and Family SES = -.15 Characterized as weak-negligible

5 Correlational Research Disadvantages: 1)correlation does not indicate causation 2) problems with self-report method Advantages: 1) can collect much information from many subjects at one time 2) can study a wide range of variables and their interrelations 3) study variables that are not easily produced in the laboratory

6 Correlational Research Definition: Seeks to establish a relation/association/correlation between two or more variables that do not readily lend themselves to experimental manipulation Disadvantages: 1) correlation does not indicate causation(6slide causation example) 2) problems with self-report method Advantages: 1) can collect much information from many subjects at one time 2) can study a wide range of variables and their interrelations 3) study variables that are not easily produced in the laboratory

7 Correlation is not Causation Three ways in which A and B may be causally related A B A causes B (either directly or indirectly) B causes A (either directly or indirectly) B A A third variable causes both A and B C A B

8 Correlations Inform Causation Causation implies Correlation Design or theory informs direction of influence Specify and measure likely third variables Control for third variables in model If association between A and B remains, then third variable explanation does not hold If A and B are causally related, they must be correlated Can model third variable effects Longitudinal design Experimental design Appeal to strong theory

9 Case In Point Lynam, D.R., Moffitt, T.E., & Stouthamer-Loeber, M.A. (1993). Explaining the relation between IQ and delinquency: Class, race, test motivation, school achievement, or self- control? Journal of Abnormal Psychology, 102, IQ is negatively correlated with delinquency Think of some ways this relationship could work. In other words, why or how might lower IQ be related to delinquency? What are other possibilities?

10 Delinquency leads to low IQ?

11 Third Variables? What are the likely candidates? Social Class Impulsivity Race What happens when they are included? Partial r = -.15 Original r = -.25 Significant relation remains

12 IQ  Delinquency via School Achievement? What happens when school achievement is included?

13 Correlational Research Definition: Seeks to establish a relation/association/correlation between two or more variables that do not readily lend themselves to experimental manipulation Disadvantages: 1) correlation does not indicate causation 2) problems with self-report method Advantages: 1) can collect much information from many subjects at one time 2) can study a wide range of variables and their interrelations 3) study variables that are not easily produced in the laboratory

14 Correlational Research Example Reformulated learned helplessness: When people find they are helpless, they ask why three dimensions of causal attributions internal-external specific-global stable-unstable internal, global, and stable attributions lead to depression Attributional Style Questionnaire Should find correlation between I, S, G attributional style and level of depression

15 Attributional Style Questionnaire You have been looking unsuccessfully for a job for some time. 1. Write down one major cause. 2. Is the cause of your unsuccessful job search due to something about you, or to, something about other people or circumstances ?Totally due to others to me 3. In the future, when looking for a job, will this cause again be present? Will never againWill always be present be present 4. Is this cause something that influences just looking for a job, or does it also influence other areas of your life? Influences this Influences all situation situations 5. How important would this situation be if it happened to you? Not at allExtremely important important

16 Quasi-Experimental Research Definition: Blends correlational and experimental approaches. Typically examines interaction between an individual difference variable and an experimental manipulation(expericorr example) Disadvantages: similar to those of correlational research 1 Third variable problem still remains Advantages: similar to those of correlational research 1 Can tease out cause and effect somewhat better if have manipulated variable

17 Quasi-experimental Example Discounting: Tendency to choose smaller, immediately available rewards over larger, delayed rewards Hypothetical Money Choice Task Choice is offered: smaller, immediately available reward or larger delayed one Chooses immediate reward, task is over and value is recorded Chooses delayed reward, new choice with larger immediate reward is offered Waiting for larger immediate reward before switching shows less discounting

18 HMCT (Version 1) or $5 now You can have: $100 in 1 week Which would you choose? $5 now $100 in 1 week

19 HMCT (Version 1) or $10 now You can have: $100 in 1 week Which would you choose? $10 now $100 in 1 week

20 HMCT (Version 1) or $15 now You can have: $100 in 1 week Which would you choose? $15 now $100 in 1 week and so on….

21 HMCT (Version 2) or $5 now You can have: $100 in 1 month Which would you choose? $5 now $100 in 1 month

22 HMCT (Version 2) or $10 now You can have: $100 in 1 month Which would you choose? $10 now $100 in 1 month

23 Hypothetical Results Effect of Condition: Version 1 $80.25 Version 2 $65.25 $65.00 Interaction of Condition and SS: Version 1 $85.25 $65.00 Version 2 $70.25 Low SS High SS

24 Quasi-Experimental Research Definition: Blends correlational and experimental approaches. Typically examines interaction between an individual difference variable and an experimental manipulation Disadvantages: similar to those of correlational research 1 Third variable problem still remains Advantages: similar to those of correlational research 1 Can tease out cause and effect somewhat better if have manipulated variable

25 Locus of Control Scale For each pair of statements, choose the one with which you most agree: 1a. Many of the unhappy things in people's lives are due partly to bad luck. 1b. People's misfortunes result from the mistakes they make. 2a. One of the major reasons we have wars is that people don't take enough interest in politics. 2b. There will always be wars, no matter how hard people try to prevent them. 3a. Sometimes I can't understand how teachers arrive at the grades they give. 3b. There is a direct connection between how hard I study and the grades I get. 4a. The average citizen can have an influence in government decisions. 4b. This world is run by the few people in power and there isn't much the little guy can do about it. Scoring: Give yourself one point for each of the following: 1a, 2b, 3a, 4b

26 Quasi-Experimental Research Locus of Control Beliefs about one’s ability to influence outcomes Similar to learned helplessness Assessed with LOC scale Selected participants to be high or low in external LOC Randomly assigned participants to one of two conditions Performance task with shock that is very easy to learn to avoid Performance task with shock that is hard to learn to avoid Findings in line with hypotheses In easy task most people learned how to avoid shock In harder task, Ps with high external LOC were less likely to learn

27 Problems to Look For Experimental confound: when another variable is allowed to vary with the independent variable. Third variable problem Nonrandom samples: when samples are selected so that not everyone has an equal opportunity to participate. Failure to replicate: single experiments do not constitute facts. Failure to include relevant comparison groups: lack an adequate baseline or normative data.(Example)

28 Failure to Include Comparison Make people happy or sad and examine effects on aggression: SadHappy Aggression The meaning depends on a control group: SadControlHappy 1) ) )


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