Do Energy Snack Bars Improve Afternoon Alertness? 100 Factory Workers

Multiple Choice

Do energy snack bars improve afternoon alertness? 100 factory workers were randomly assigned to two groups.One group ate energy snack bars at lunch and the other group ate placebo snack bars.At the afternoon break (approximately 1-1/2 hour after lunch) , a significant increase in alertness was observed.Later analysis of the experiment results showed 87% of the participants exhibiting increased alertness were from the group which ate energy snack bars.

A) Single blind, only participant is blinded
B) Single blind, only evaluator is blinded
C) Double blind
D) Neither