title: Application of a mixed model approach for assessment of interventions and evaluation of programs.
abstract: Many social programs and programs for prevention of drug use are designed to affect a wide variety of targets, including individuals, families and neighborhoods, and organizations such as schools, companies, or hospitals. The nature of the intervention and the design of the particular study determine the choice of the appropriate unit of analysis in assessments of outcome. When the units of assignment and units of observation differ from one another, that is, when clusters of persons rather than persons are assigned at random to treatments, analyses performed at lower levels in the study hierarchy provide inefficient estimates of parameters and often lead to inappropriate significance tests. The present goal was to illustrate the applications of linear mixed models for evaluating statistically the effectiveness of programs.
authors.affiliation: University of Oviedo. gvallejo@correo.uniovi.es
authors.forename: G
authors.initials: G
authors.lastname: Vallejo
authors.forename: J R
authors.initials: JR
authors.lastname: Fernández
authors.forename: R
authors.initials: R
authors.lastname: Secades
mesh_terms: D000437:Alcoholism / Q000517:prevention & control*; D015982:Bias; D016000:Cluster Analysis; D003156:Community Mental Health Services / Q000706:statistics & numerical data*; D006293:Health Promotion / Q000706:statistics & numerical data*; D006801:Humans; D016014:Linear Models; D001523:Mental Disorders / Q000517:prevention & control*; D017063:Outcome Assessment, Health Care / Q000706:statistics & numerical data; D015397:Program Evaluation / Q000706:statistics & numerical data*; D016032:Randomized Controlled Trials as Topic / Q000706:statistics & numerical data; D012949:Social Work, Psychiatric / Q000706:statistics & numerical data*; D019966:Substance-Related Disorders / Q000517:prevention & control*