Threats to Validity in Experiments The John Henry Effect
Threats to Validity in Experiments The John Henry Effect
Threats to Validity in Experiments The John Henry Effect
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<strong>Threats</strong> <strong>to</strong> <strong>in</strong>ternal validity <strong>in</strong> experiments (4)<br />
• Treatment misidentification: <strong>The</strong> treatment isn’t what we th<strong>in</strong>k it is<br />
• Hawthorne effect: What did researchers th<strong>in</strong>k the treatment was? What else was<br />
part of the “treatment”?<br />
• Experimenter expectations: <strong>The</strong> need (<strong>in</strong> some cases) for double-bl<strong>in</strong>d experiments<br />
• Voter education <strong>in</strong> Georgia (the country)<br />
• Villages are randomly assigned <strong>to</strong> treatment and control<br />
• “Educa<strong>to</strong>rs” go door <strong>to</strong> door <strong>in</strong> the treatment group villages and provide residents<br />
with <strong>in</strong>formation on the election date, the issues, and the candidates.<br />
• No one goes door <strong>to</strong> door <strong>in</strong> the villages <strong>in</strong> the control group.<br />
• Results: Treatment villages experience lower voter turnout than the control villages.<br />
• What did researchers th<strong>in</strong>k the treatment was?<br />
• What else might have been part of the “treatment”, and how might this have<br />
negatively affected voter turnout?<br />
SOCI 60: Lecture 16<br />
Benjam<strong>in</strong> Graham
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