| Placebo | Two glasses of water, salt | Bring out two glasses of water. Stir salt into only one glass. The glasses will look the same, but one now has an “active ingredient”—the salt. | A placebo is a word that refers to something that looks like medicine but isn’t, and has no effect on the person who takes it.
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| Double-blinded | Two glasses of water, sugar | Bring out two glasses of water. Ask someone from the audience to pour the sugar in without anyone else seeing them do it. Ask the audience to guess which glass has sugar in it. | Neither the participants nor the researchers know which participants are receiving the test drug and which are receiving the placebo. |
| Randomization | Paint a cardboard box to look like a die, each side with a different number of dots from 1 to 6. | Ask each person to roll the die and remember the number that appears on top of the box. Divide the group according to these numbers: 1 to 3 on one side of the room; 4 to 6 on the other. | When people are randomly assigned to either the intervention group or the placebo group of a study, the only determining factor is chance. |