Outline. Case Studies & Testimonials Case studies as evidence The placebo effect The vividness issue Correlation & Causation Third variable problem Directionality Selection bias. Case studies & testimonials. Case studies in-depth analyses of particular individuals
Bower (1996): Placebo effect of Prozac twice as large as effect of the drug itself.
Greenberg & Fisher
The limits of biological treatments for psychological distress: comparisons with psychotherapy & panacea (1989)
From placebo to panacea: Putting psychiatric drugs to the test (1997)Placebo effects
Brown (SciAm 1998): expectations have real, measurable effects – prescribe placebos!Placebo effects
Placebo effects are widespread, so they are always present as an alternative account of why someone got better when they got a therapy.
You cannot rule out placebo effects in case studies.
People who got the benefit of placebo effects may offer testimonials, not knowing that it wasn’t their therapy that made the difference.Placebo effects- conclusions
In the new (8 as an alternative account of why someone got better when they got a therapy.th) edition of his book, Stanovich has added a qualification to his comments about vividness, acknowledging that he uses vivid examples himself.
He now says that he uses vivid examples to make his points memorable, but he also provides citations to scientific evidence for those points. The latter constitute “proof” of those points.The Vividness Issue
Stanovich says that he uses vivid examples only because they are memorable – so in his mind, presumably, the reader will be persuaded by the cited scientific studies, not the vivid examples
But will this be the case? Will his distinction between “illustration” and “proof” be as important to readers as it is to him?The Vividness Issue
1. Do vivid examples prove claims?
2. Are ordinary people unsophisticated consumers of evidence?
3. Does vividness play any useful role in our thinking?
Paper was scarce, so she wrote in tiny letters, with a magnifying glass
Wrote a novel about the German occupation of France
Arrested by French police in July 1942 in front of her two young daughters.
Told the daughters she was going away on a tripIrène Némirovsky
Husband arrested, died in Auschwitz gas chamber in November 1942
Daughters guarded by Catholic nuns & priests through the war, and provided for by Irène’s publisher & a friend during and after the warIrène Némirovsky
Daughters survived the war, kept a suitcase containing their mothers’ last writings.
30 years later, daughter Dianne spent 20 years transcribing Irène’s novel Suite Francaise, working with a magnifying glass.
Book was published in France in 2004, and a tremendous success – though Némirovsky had been long forgotten.
Published in Canada in April 2007Irène Némirovsky
So, which helps you understand the horror of the Holocaust better – the statistic, “6 million murdered” – or the story of Irène Némirovsky?
Both are important, but in different ways
So, vividness can be an important aid to thought
And if vivid examples are filtered through many people’s evaluations, perhaps that process produces a useful conclusionVividness
Basic point: Correlation does not imply causation better – the statistic, “6 million murdered” – or the story of Ir
Goldberger example: cause of pellagra
Goldberger used a manipulation to test causal accounts
He put the germ theory in jeopardy – and showed that it was wrong
He also put his diet theory in jeopardy – and showed that it was right.Correlation and Causation
Relationship between two variables A and B might be produced by a third variable which influences both.
E.g., correlation between # of births in German cities and # of storks in German cities, in 19th century.
# Families # houses # chimneys # storksThird variable problem
Poor reading example: researchers once thought that poor reading caused by improper eye-movements.
We now know that causation works in the other direction: poor reading skill produces impaired eye-movements.Directionality
Self-esteem and academic achievement – lots people have claimed that low self-esteem leads to low academic achievement.
In self-esteem case, there is evidence that poor academic achievement leads to low SE and good academic achievement leads to high SE (other things being equal)Directionality
relationship between subject and environmental variables arises because people with different characteristics select different types of environments.
E.g., Arizona and respiratory illness.
SAT scores & teacher salaries exampleSelection bias