12.11 Statistical Literacy

Research on the effectiveness of surgery for weight loss reported here found that "The surgery was associated with significantly greater weight loss [than the control group who dieted] through 2 years (61.3 versus 11.2 pounds, P<0.001)."

What test could have been used and how would it have been computed?

What do you think?

For each subject a difference score between their initial weight and final weight could be computed. A t test of whether the mean difference score differs significantly from 0 could then be computed. The mean difference score will equal the difference between the mean weight losses of the two groups (61.3 - 11.2 = 50.1).

Adapted from Online Statistics Education: A Multimedia Course of Study (onlinestatbook.com), Project Leader: David M. Lane, Rice University. Developed with NSF support. The original work is in the public domain; it is cited here at the authors' request. Changes were made: reformatted as an accessible XYZ web edition with native MathML. License: Public-Domain.