"What is Significance?"Discussion Excerpt A study (Lee et al., 2010) published in the Journal of the American Medical Association (JAMA) investigated the association between physical activity and long-term weight gain in middle-aged women who consumed a usual diet. The study received widespread media attention because it refuted the federal exercise guideline at the time, which recommended at least 150 minutes per week of moderate physical activity for substantial health benefits. The study has since been cited repeatedly in medical literature in favor of much different exercise recommendations. The study was a prospective cohort design following 34,079 healthy women (mean age 54.2 years) over a 13- year period, deeming it a study of high statistical power by conventional research standards. Researchers compared average weight gain in 3 exercise intensity groups: low intensity (<7.5 MET-hours/week, equivalent to 150 minutes per week of moderate exercise, moderate intensity (7.5 to <21 met-hoursweek), and high intensity (>21 MET-hours/week, equivalent to 420 minutes per week of moderate exercise). Measurements were taken at baseline (beginning of the study) and at approximately three year intervals through the duration of the study. Statistical analysis included adjustment for several extraneous variables (age, BMI, smoking status, menopausal status) that could also affect the physical activity-weight gain relationship. As expected, all groups gained weight over time. The change in weight for all groups for the entire period was similar, with a mean of 5.7 pounds. The high-intensity group gained significantly less weight than moderateintensity (p=.003) and low-intensity groups (p=.002). During any 3-year interval, those in the low and moderate groups gained an average of .26 pounds and .24 pounds more than the high-intensity group. Over the 13-year period of the study, high-intensity exercisers saved an average of approximately 1 pound of weight gain compared to the other groups.

There were no significant relationships between age, smoking status, or menopausal status and activity-weight gain, meaning that these factors did not affect the results in any way. There was significant relationship for Body Mass Index (an indication of body fatness) such that women with a low BMI (< 25 kg/m2 ) gained less weight with high levels of physical activity (p<.0001), but no significant relationship between high physical activity and less weight gain among heavier women with BMI 25-30 kg/m2 (p=.56) and >30 kg/m2 (p=.50). Based on their results, researchers concluded that middle-aged women require at least 60 minutes per day (420 minutes per week) of moderate-intensity exercise to prevent unhealthy weight gain. This conclusion dispelled the previous federal recommendation of 150 minutes per week for "substantial health benefits." In addition, the researchers concluded that once a woman is overweight (i.e., BMI >25 kg/m2), it may be "too late" to prevent further weight gain since physical activity was not associated with less weight gain in those groups.

In your first discussion post, respond to the following questions.

Identify the statistical significance in this study based upon the information presented. Provide specific data/details to support this.

Are the results of this study clinically significant or not? Explain your reasoning.

What is your appraisal of the researchers' conclusions? Are they logical? Discuss the real-world implications of the researchers' conclusions. How does this relate to the concepts addressed in this discussion?

Locate a resource that can help one understand the concept of statistical versus clinical significance. Provide the reference or link to the source.

Your post should be approximately two hundred fifty words. Please support your statements with at least one credible source.