Chapter 3 Detailed Learning Objectives 1.Identify variables and distinguish a variable from its levels (or values). 2.Discriminate between measured and manipulated variables. 3.Describe a variable both as a conceptual variable and as an operational definition. 4.Indicate how many variables frequency, association, and causal claims typically involve. 5.Describe positive, negative, and zero associations. 6.Identify verbs that signal causal claims versus association claims. 7.Apply the three criteria that are used to evaluate a causal claim: covariance, temporal precedence, and internal validity. 8.Identify examples in which writers’ and researchers’ claims are not justified by the studies they are describing. 9.Appreciate that few studies can achieve all four kinds of validity at once, so researchers must prioritize some validities over others.
1. Three necessary criteria for causal claims are A. covariance, temporal precedence, and internal validity. B. association, construct validity, and generalizability. C. operationalization, temporal precedence, and construct validity. 2. An association claim has A. one variable. B. two manipulated variables. C. two or more measured variables. 3. Frequency claims A. are also known as anecdotal claims. B. can describe a particular rate or level in something. C. need to have internal validity. D. All of the above. 4. According to the textbook, the conclusion that family meals prevent eating disorders cannot be supported because A. the study does not establish temporal precedence or internal validity. B. there is zero association between the variables. C. they covary positively. D. they manipulate too many variables. Reading Quiz
Practice Identifying Claims a.Worry may make women’s brains work overtime. b.High “normal” blood sugar may still harm brain. c.Want a higher GPA? Go to a private college. d.Those with ADHD do one month’s less work a year. e.When moms criticize, dads back off baby care. f.Report: 16% of teens have considered suicide. g.MMR shot does not cause autism, large study says. h.Breastfeeding may boost children’s IQ. i.Breastfeeding rates hit new high in United States. j.Smiling may lower your heart rate. k.OMG! Texting and IM-ing doesn’t affect spelling! l.Facebook users get worse grades in college. m.Mother’s heartburn means a hairy newborn.
Practice Identifying Claims: Continued a.Indicate if the claim is frequency, association, or cause. b.For each claim, identify the variable(s). c.For each variable, is it manipulated or measured? d.State each variable at the conceptual level. e.State each variable in terms of its operational definition: How might it have been operationalized?
Association Claims: Types of Associations Draw a scatterplot for each of the following claims: Facebook users get worse grades in college. OMG! Texting and IM-ing doesn’t affect spelling! Mother’s heartburn means a hairy newborn. What kind of association is the one you drew? (positive, negative, zero?)
Interrogating the Three Claims Using the Four Big Validities
Review: Variables Three claims Types of associations
Interrogating the Three Claims Using the Four Big Validities Interrogating frequency claims Interrogating association claims Interrogating causal claims
Construct validity: Quality of the measures and manipulations External validity: To whom, what, or where can we generalize? Statistical validity: Statistical conclusions are appropriate and reasonable. Internal validity: No alternative causal explanations for the outcome
Interrogating Frequency Claims Construct validity of the variable How well was the variable measured? External validity is essential! Can we generalize from the sample to the population? Statistical validity How large is the margin of error?
Interrogating Association Claims Construct validity of each variable How well was each variable measured? Statistical validity How strong is the association? Is it statistically significant? External validity To whom or what can we generalize the association? May be less important to the researcher.
Interrogating Causal Claims Construct validity of the two variables How well was the independent variable manipulated? How well was the dependent variable measured? Statistical validity How big is the difference? Is it statistically significant? External validity To whom or what can we generalize this effect? External validity is rarely prioritized in an experiment Internal validity This is the priority!
Three Criteria for Causation Covariance Temporal precedence Internal validity
1.Does recalling the Ten Commandments make you less likely to cheat in the matrix task? “We took a group of 450 participants, split them into two groups, and set them loose on our usual matrix task. We asked half of them to recall the Ten Commandments and the other half to recall 10 books that they had read in high school. Among the group who recalled the 10 books, we saw the typical widespread but moderate cheating. But in the group that was asked to recall the Ten Commandments, we observed no cheating whatsoever.” 2. A recent study showed that “Corporal punishment was associated with increased odds of anxiety and mood disorders, including major depression, panic disorder, post-traumatic stress disorder, agoraphobia, and social phobia. Several personality disorders and alcohol and drug abuse were also linked to physical punishment, the researchers found.”
Three Claims, Four Validities Find examples of each kind of claim in your headlines. Write down a question to ask of the study, or of the journalist, for each of the appropriate validities. If you think a validity is not relevant, explain why not.
FrequencyAssociationCausal Variables in the claim: Construct validity question Statistical validity question Internal validity question External validity question Three Claims, Four Validities Matrix
Prioritizing Validities Which validity is appropriate to interrogate for every study? Which validities are not always relevant for a study? Why can’t researchers achieve all four validities in a single study? Which two validities are most often in trade-off? Which validity is most under the researcher’s control? That study’s just not valid!
The question is, is the study valid? That is not a valid study. Say this: Not that: How’s the construct validity? Is external validity relevant here? Can the study support a causal claim?