title: Addressing selection bias in dental health services research.
abstract: When randomization is not possible, researchers must control for non-random assignment to experimental groups. One technique for statistical adjustment for non-random assignment is through the use of a two-stage analytical technique. The purpose of this study was to demonstrate the use of this technique to control for selection bias in examining the effects of the The Supplemental Program for Women, Infants, and Children's (WIC) on dental visits. From 5 data sources, an analysis file was constructed for 49,512 children ages 1-5 years. The two-stage technique was used to control for selection bias in WIC participation, the potentially endogenous variable. Specification tests showed that WIC participation was not random and that selection bias was present. The effects of the WIC on dental use differed by 36% after adjustment for selection bias by means of the two-stage technique. This technique can be used to control for potential selection bias in dental research when randomization is not possible.
authors.affiliation: Department of Pediatric Dentistry, School of Dentistry, University of North Carolina, Chapel Hill, NC 27599-7450, USA. jessica_lee@dentistry.unc.edu
authors.forename: J Y
authors.initials: JY
authors.lastname: Lee
authors.forename: R G
authors.initials: RG
authors.lastname: Rozier
authors.forename: E C
authors.initials: EC
authors.lastname: Norton
authors.forename: W F
authors.initials: WF
authors.lastname: Vann
mesh_terms: D000328:Adult; D000385:Aid to Families with Dependent Children; D002675:Child, Preschool; D015331:Cohort Studies; D003627:Data Interpretation, Statistical; D003695:Delivery of Health Care; D019140:Dental Care for Children / Q000706:statistics & numerical data*; D003752:Dental Health Services / Q000706:statistics & numerical data; D003753:Dental Health Surveys; D018865:Dental Research / Q000379:methods; D005260:Female; D006297:Health Services Accessibility / Q000706:statistics & numerical data*; D006302:Health Services Research / Q000379:methods*; D006801:Humans; D007223:Infant; D016015:Logistic Models; D008137:Longitudinal Studies; D008297:Male; D008484:Medicaid / Q000706:statistics & numerical data; D018803:Models, Economic; D016032:Randomized Controlled Trials as Topic / Q000379:methods; D012044:Regression Analysis; D015983:Selection Bias; D012959:Socioeconomic Factors; D014481:United States