A district pilots a new math instruction program in one school; during the pilot, teachers in other schools continue with the old method and student scores improve. Which phenomenon best explains this change?

A district pilots a new math instruction program in one school; during the pilot, teachers in other schools continue with the old method and student scores improve. Which phenomenon best explains this change?

• A. John Henry effect
• B. Placebo effect
• C. Hawthorne effect
• D. Experimenter bias

Answer: (A)

This best aligns with the John Henry effect. When a district runs a pilot in only one school, the other schools are known not to be receiving the new program. The control group (those not getting the new instruction) may feel pressure to perform well or to “outdo” the experimental group, leading them to push harder and show gains despite not using the new method. This motivation driven by awareness of the study and comparison to the treatment group explains the observed improvement. This is different from the Hawthorne effect, where any group improves simply because they know they’re being observed. It’s also distinct from the placebo effect (improvement from believing they’re receiving treatment) and from experimenter bias (the researcher’s expectations influencing results).

This best aligns with the John Henry effect. When a district runs a pilot in only one school, the other schools are known not to be receiving the new program. The control group (those not getting the new instruction) may feel pressure to perform well or to “outdo” the experimental group, leading them to push harder and show gains despite not using the new method. This motivation driven by awareness of the study and comparison to the treatment group explains the observed improvement.

This is different from the Hawthorne effect, where any group improves simply because they know they’re being observed. It’s also distinct from the placebo effect (improvement from believing they’re receiving treatment) and from experimenter bias (the researcher’s expectations influencing results).