Research designs :Research designs headlessprofessor


Objective :Objective Describe the logic of science


Purpose of Science :Purpose of Science Understand


Purpose of Science :Purpose of Science Understand Predict


Purpose of Science :Purpose of Science Understand Predict Control


Logic of science :Logic of science


Example :Example Marriage helps increase your happiness.


Hypothesis :Hypothesis A prediction as to the results you expect to find


Hypothesis = a prediction which guides research :Hypothesis = a prediction which guides research (hypotheses are generated by theories, but are testable by data)


Population = entire class of subjects studied :Population = entire class of subjects studied


Sample = those subjects actually observed :Sample = those subjects actually observed Should be large and representative of the population


Group :Group A subsample


Group :Group A subsample Determined by background factors


Group :Group A subsample Determined by background factors Assigned in experiments


Research Design #1 :Research Design #1 Sample vs. Norms


Representative Sample :Representative Sample One that does not over-represent or under-represent any particular segment within the population


Representative Sample :Representative Sample Does not over-represent or under-represent any particular segment within the population The proportion of sub-samples (groups) in the sample should match the proportion of these segments of the population


Hypothesis :Hypothesis Married people should be happier than average.


Confounding variables :Confounding variables Anything leading to sampling bias


Confounding variables :Confounding variables Anything leading to sampling bias Geography


Confounding variables :Confounding variables Anything leading to sampling bias Geography Elapsed time


Research Design #2 :Research Design #2 Separate groups


Experiments manipulate an independent variable :Experiments manipulate an independent variable Separate groups (subjects are randomly assigned and then treated differently): between subjects comparison on DV


Separate groups design :Separate groups design


A placebo helps control patient expectations :A placebo helps control patient expectations New med is given to experimental group Placebo is given to control group Pills taste the same Patients do not know which is which Researchers measuring DV do not know until after data are collected


Hypothesis :Hypothesis Married people should be happier than unmarried people.


Confounding variables :Confounding variables Anything influencing grouping


Confounding variables :Confounding variables Maybe happy people are more likely to find spouses


Confounding variables :Confounding variables Maybe happy people are less likely to get divorced


Research Design #3 :Research Design #3 Repeated measures


Experiments manipulate an independent variable :Experiments manipulate an independent variable Separate groups (subjects are randomly assigned and then treated differently): between subjects comparison on DV Repeated measures (entire sample is measured on DV before and after the treatment): within subjects comparison


Repeated measures design :Repeated measures design


Problems with repeated measures experiments :Problems with repeated measures experiments Fatigue & boredom effect Practice effect Natural course of a disorder Attrition of subjects changes the sample


Hypothesis :Hypothesis People should be happier after marriage than before.


Confounding variables :Confounding variables Maturation


Confounding variables :Confounding variables Maturation Change in wealth


Confounding variables :Confounding variables Maturation Change in wealth Historical periods


Research Design #4 :Research Design #4 correlational


Hypothesis :Hypothesis People who have been married longer should be happier.


Confounding variables :Confounding variables Age


Confounding variables :Confounding variables Age Cohort


Research designs :Research designs headlessprofessor