The article “Effect of Wearable Technology Combined With a Lifestyle Intervention on Long-term Weight Loss” (JAMA 2017: 1161–1171) describes a study in which adults in a large cohort were provided the same weight-loss regimen for six months. Then, participants were randomly assigned to either (1) self-monitor diet and physical activity using a Web site or (2) track diet and physical activity with a wearable device and accompanying Web interface. The weights of all subjects (in kg) were recorded at the beginning of the study and 24 months later. The following summary is consistent with information in the article.

a. Construct and interpret a 95% confidence interval for the population mean weight loss under the first treatment (self-monitoring with a Web site).
b. Construct and interpret a 95% confidence interval for the population mean weight loss under the second treatment (tracking with a wearable device).
c. How confident can you be that both the intervals in (a) and (b) contain the values of population mean weight loss?
d. Does the data show at the .05 level that the two population means in parts (a) and (b) are different? Perform the appropriate hypothesis test.

Transcribed Image Text:

Treatment (1) (2) n = 233 Mean: SD: n = 237 Mean: SD: Baseline 24 Months Difference 95.2 -5.9 16.4 6.9 96.3 -3.5 16.5 7.3 89.3 15.1 92.8 15.7