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From: Dr. Mitchell
Date: 25 Apr 2007
Time: 21:33:00 -0400
Remote Name: 151.161.36.66
Power is your ability to find an effect if it exists. It is influenced by your sample size, range restriction, and measurement error. For this study, the sample size was low, which means the power was probably low. The variability in the independent variable is also relatively low - in the drug use group, they only had a range of 4 yrs of drug use (1 - 5 years), which also may have decreased the ability to find an effect of drug use. Remember, although the researchers found some significant effects, they didn't find all of them that they were expecting.