Although there is popular believe that herbal remedies such as melatonin can decrease the time it takes to fall asleep these effects are typically not supported in a controlled study. The average individual takes 13 minutes to fall asleep with a standard deviation of 3 minutes. A researcher obtained a sample of 25 individuals and gave them a standard dose of melatonin before sleep. The sample participants fell asleep in an average of 11. 5 minutes. The researcher wishes to test the claim that individuals taking melatonin fall asleep faster than those not taking the supplement.

Compute Cohens d to estimate the size of the effect?