- Excess Body Weight and Sleep Apnea
Research conducted by
Kari Johansson, Erik Hemmingsson, Richard Harlid, Ylva Trolle Lagerros, Fredrik Granath, Stephan Rössner, and Martin Neovius
Statistical article authored by
Case study prepared by
Robert F. Houser and Georgette Baghdady
In his statistical article, “Standard deviation versus standard error,” UK researcher Philip Sedgwick presents us with an interesting discussion of the proper use of standard deviation (SD) and standard error of the mean (SEM). He uses an example of a weight loss study of \(63\) obese men suffering from obstructive sleep apnea who were being treated with continuous positive airway pressure (CPAP). The weight loss program lasted one year. Outcome measures included change in body weight measured in kilograms (kg).
More than \(60\%\) of people experiencing obstructive sleep apnea are obese. CPAP therapy is the most common treatment. It uses a machine and mask to prevent the airway from collapsing, thus enabling a person to breathe more easily during sleep. Weight loss is an effective treatment for sleep apnea.
Questions to Answer
What is the proper use of the SD? What is the proper use of the SEM?
None for the Sedgwick article.
Descriptions of Variables
|Weight||Body weight at baseline in kg|
|Weight change||Change in body weight at one year from baseline in kg|
What Is Sleep Apnea?
t Table (two-tailed) for significance and calculation of confidence interval
Johansson et al. article
- Sedgwick, P. (2011). Standard deviation versus standard error. BMJ, 343, d8010.
- Johansson, K., Hemmingsson, E., Harlid, R., Lagerros, Y. T., Granath, F., Rössner, S., Neovius, M. (2011). Longer term effects of very low energy diet on obstructive sleep apnoea in cohort derived from randomised controlled trial: prospective observational follow-up study. BMJ, 342, d3017.
Online Statistics Education: A Multimedia Course of Study (http://onlinestatbook.com/). Project Leader: David M. Lane, Rice University.