title: Application of potential outcomes to an intentional weight loss latent variable problem.
abstract: Studies that explore the link between weight loss among obese individuals and mortality have met with mixed results. One possible explanation is that total weight loss may have contributions from weight loss that is intentional and weight loss that is unintentional. The latter may be due to some underlying condition that has a deleterious effect on subsequent mortality. Some studies have then focused on subjects who intend to lose weight. However, in a population there is no guarantee that weight loss among these individuals is due only to their intention. This paper extends the work of Coffey et al., (2005) who treated intentional weight loss as a latent variable. In particular, the problem is reformulated using potential outcomes. This formulation more clearly identifies a nonestimable correlation that arises because of the latent variable, and it allows for the incorporation of covariate information that can tighten estimable bounds for this correlation. We show in a data set from an experiment on mice that substantial tightening of bounds is possible with a covariate that is predictive of weight loss. These bounds can then, in turn, be used to estimate bounds on a causal parameter in a linear model.
authors.affiliation: Department of Statistics, Kansas State University, Manhattan, KS 66506.
authors.forename: Gary L
authors.initials: GL
authors.lastname: Gadbury
authors.forename: Thidaporn
authors.initials: T
authors.lastname: Supapakorn
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Coffey
authors.forename: Scott W
authors.initials: SW
authors.lastname: Keith
authors.forename: David B
authors.initials: DB
authors.lastname: Allison
references.citation: Ala J Med Sci. 1987 Oct;24(4):435-42
references.pmid: 3310711
references.citation: Obes Rev. 2003 Feb;4(1):9-16
references.pmid: 12608523
references.citation: Diabetes Care. 2004 Mar;27(3):657-62
references.pmid: 14988281
references.citation: Am J Clin Nutr. 2004 Aug;80(2):466-74
references.pmid: 15277172
references.citation: Biometrics. 2000 Sep;56(3):882-5
references.pmid: 10985231
references.citation: Nutrition. 1996 Nov-Dec;12(11-12):819-20
references.pmid: 8974111
references.citation: Int J Body Compos Res. 2008;6(4):185-192
references.pmid: 25285041
references.citation: Am J Epidemiol. 1997 Aug 15;146(4):339-49
references.pmid: 9270413
references.citation: Ann Intern Med. 1991 Dec 1;115(11):901-5
references.pmid: 1952480
references.citation: Int J Obes Relat Metab Disord. 1999 Jun;23(6):603-11
references.pmid: 10411233
references.citation: Ann Intern Med. 2003 Mar 4;138(5):383-9
references.pmid: 12614090
references.citation: Annu Rev Psychol. 2002;53:605-34
references.pmid: 11752498
references.citation: Med Hypotheses. 2002 Nov;59(5):568-76
references.pmid: 12376081
references.citation: Stat Med. 2005 Mar 30;24(6):941-54
references.pmid: 15717333
references.citation: Int J Obes Relat Metab Disord. 2001 Jul;25(7):1071-8
references.pmid: 11443509
references.citation: PLoS Med. 2005 Jun;2(6):e171
references.pmid: 15971946
references.citation: Biometrics. 2002 Mar;58(1):21-9
references.pmid: 11890317
references.citation: Proc Natl Acad Sci U S A. 1999 Apr 13;96(8):4730-4
references.pmid: 10200330
references.citation: Obes Rev. 2003 Feb;4(1):3-7
references.pmid: 12608522
references.citation: Int J Epidemiol. 2006 Feb;35(1):179-80
references.pmid: 16394115
references.citation: Eat Behav. 2001 Summer;2(2):87-95
references.pmid: 15001038
references.citation: Biom J. 2005 Oct;47(5):662-73
references.pmid: 16385907