Case example for Blinding

Case example for Blinding

Definition : Blinding is a technique used to decrease bias on the part of the researcher or the participant in which the participant or both the researcher and the participant are not told to which group they have been assigned.

In a study investigating the effects of a new anti-itch cream, participants with minor skin rashes were randomly divided into one of three groups. In the first group, participants received a new anti-itch cream that contained 3% hydro-cortisone. In the second group, the participants received the standard cream available over-the-counter which contains 1% hydrocortisone. The third and final group members received a cream that contained 0% hydrocortisone. The participants did not know to which group they were assigned. Participants used the cream for three days to relieve itching symptoms caused by the rash. After three days, each participant’s rash was examined to determine if itching symptoms subsided. If this was not the case, the participant was provided with the standard treatment which is known to relieve itching.

Discussion questions

1. Why are participants not told (blind to) their group assignment?

2. Is this a single or double blind study?

3. Do you think knowledge of group assignment (no blinding) would affect the results? Why or why not?

4. Do you think that the researcher’s knowledge of group assignment would affect the results? Why or why not?

		ORI Curriculum Examples

	Case example for Blinding Definition : Blinding is a technique used to decrease bias on the part of the researcher or the participant in which the participant or both the researcher and the participant are not told to which group they have been assigned. In a study investigating the effects of a new anti-itch cream, participants with minor skin rashes were randomly divided into one of three groups. In the first group, participants received a new anti-itch cream that contained 3% hydro-cortisone. In the second group, the participants received the standard cream available over-the-counter which contains 1% hydrocortisone. The third and final group members received a cream that contained 0% hydrocortisone. The participants did not know to which group they were assigned. Participants used the cream for three days to relieve itching symptoms caused by the rash. After three days, each participant’s rash was examined to determine if itching symptoms subsided. If this was not the case, the participant was provided with the standard treatment which is known to relieve itching. Discussion questions 1. Why are participants not told (blind to) their group assignment? 2. Is this a single or double blind study? 3. Do you think knowledge of group assignment (no blinding) would affect the results? Why or why not? 4. Do you think that the researcher’s knowledge of group assignment would affect the results? Why or why not?