The statistical power for the study was modeled with a two-tailed paired sample t-test to test changes in SDSCA from baseline to three months. Published studies using the SDSCA have shown effects sizes of change in intervention groups ranging from .278 to .53. Thus, conservatively estimating an effect size of .278, to achieve 80% power at a p <.05 significance level, a sample of 125 participants will be required, assuming a 20% longitudinal attrition rate. Attrition rates in the 10% to 20% range have been reported in previous similar Web-based intervention studies.