PSYC 2301 Ch 4 - Lecture notes Chapter 4 PDF

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Research Design Fundamentals ...

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PSYC 2301 Ch 4 Research Design Fundamentals Variables ● ● ●

Variables: Any event, situation, behaviour, or individual characteristic that varies 2 or more levels Ex: age room temperature

Non-Experimental vs. Experimental Methods ●

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Non-experimental Method: no manipulation of variables; correlational ○ Goal to describe of behaviour ○ Ex: exercise and happiness Experimental Method: manipulation of variables ○ Goal to explain behaviour Independent: variable we are changing Dependent: variable we are measuring

Operational Definitions of Variables ● ● ●

Defines the operations or techniques the researcher will use to measure or manipulate a variable. Necessary for empirical study Help communicate ideas to others

Variable Types ●

Three general categories ○ Situational variables - describes characteristics of a situation or environment ■ Ex: number of works, number of people; measured/manipulated ○ Response variables - responses or behaviour of people ■ Ex: reaction time ○ Participant variables -

Operational Definitions of Variables ●

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Many ways to operationally define the same construct ○ Example: hunger, aggression (hunger predicts aggression) ■ Ex: hunger: not eating for 5 hours Whether an operational definition really measures a construct is up for debate

Confounds ●

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Variables that are intertwined with another variable so that you cannot determine which of the variables is operating ○ Example: intelligence, class grades, conscientiousness ○ Ex: correlation between wine and health Can invalidate or weaken research ○ Ex: thinking about fast food makes people impatient - logo vs blank square

Relationships Between Variables ● ● ● ●

Positive Linear Relationship: increases in one variable relate to increases in another Negative Linear Relationship: increases in one variable relate to decreases in another Curvilinear Relationship: increases in one variable relate to both increases and decreases in another No Relationship: increases in one variable lead to no systematic changes in the other variable

Mediated Relationship ○

Mediating variable - a psychological process that occurs between two variables that helps to explain their relation ■ Ex: focused attention - behav., prosocial concerns peer problems)

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Important for explaining and for applied purposes

Interpreting Correlations ○ ○

A positive linear relation means higher scores on one make it more likely  one will have higher scores on the other It does not make it inevitable - always room for error

Interpreting Non-Experimental Results ●

Cannot make causal statements, because: ○ Cannot establish temporal precedence ○ Cannot rule out the“Third-Variable” problem

Experimental Methods: ○

Cause and effect relationships between independent and dependent variables ■ IV - considered to be the “cause”; usually manipulated by researcher ■ DV - considered to be “effect”; usually measured by researcher

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Can make causal statements because ■ Can establish covariation ■ Can establish temporal precedence ■ Eliminates most alternative explanations

Independent: laptop or no laptop Dependent: scores

Experimental Methods ○ ○ ○

Experimental control - treating participants in each group similarly in all ways other than the independent variable Random assignment – participants assigned to condition at random; all participants have an equal chance of being in each condition If both done, can conclude causality

Causality & Internal Validity ● ●

Internal validity: the ability to determine causation ( all 3 criteria); keep variables constant ○ Ex: exercise/happiness/break Necessary & sufficient causation; rare in psychology ○ Ex: reading the material & high exam score

Experimental Method: Issues to Consider ● ● ● ●

Artificiality of experiments; field experiments ○ Ex: Vancouver rental market Ethical and practical considerations ○ Ex: child-rearing, alcoholism Descriptive research ○ Ex: piaget Causation or description or prediction ○ Ex: crime...