Comparing Two Treatments
Aligned to S-IC.B.5 — Common Core State Standards for Mathematics.
What this lesson teaches
In a randomized experiment, subjects are randomly assigned to two treatments and the results compared. To judge whether a difference is real or due to chance, you simulate re-shuffling the data many times and see how often chance alone gives a difference that large.
Worked example
A drug group's pain drops 8 points; the placebo group's drops 3, a difference of 5. To test it, pool all results and randomly re-split into two groups many times. If a gap of 5 rarely appears by chance, the treatment difference is significant.
Practice questions
- State the observed difference: group A gains 12, group B gains 7.
- Why does random assignment strengthen the comparison?
- In a simulation, a difference this large happened 2% of the time: is it significant?
Watch the lesson
Every lesson comes with a video taught in English and Spanish — the same video the QR code in the printed workbook opens.
▶ Watch this lessonEn español
Comparar Dos Tratamientos
En un experimento aleatorizado, los sujetos se asignan al azar a dos tratamientos y se comparan los resultados. Para juzgar si una diferencia es real o por azar, simulas volver a mezclar los datos muchas veces y observas con qué frecuencia el azar por sí solo produce una diferencia tan grande.
Ejemplo: El grupo con el medicamento reduce el dolor 8 puntos; el grupo con placebo lo reduce 3, una diferencia de 5. Para probarlo, junta todos los resultados y vuelve a dividirlos al azar en dos grupos muchas veces. Si una diferencia de 5 rara vez aparece por azar, la diferencia del tratamiento es significativa.
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