BackgroundMultiple imputation is becoming increasingly popular. Theoretical considerations as well as simulation studies have shown that the inclusion of auxiliary variables is generally of benefit.MethodsA simulation study of a linear regression with a response Y and two predictors X1 and X2 was performed on data with n = 50, 100 and 200 using complete cases or multiple imputation with 0, 10, 20, 40 and 80 auxiliary variables. Mechanisms of missingness were either 100% MCAR or 50% MAR + 50% MCAR. Auxiliary variables had low (r=.10) vs. moderate correlations (r=.50) with X’s and Y.ResultsThe inclusion of auxiliary variables can improve a multiple imputation model. However, inclusion of too many variables leads to downward bias of regression coefficients and decreases precision. When the correlations are low, inclusion of auxiliary variables is not useful.ConclusionMore research on auxiliary variables in multiple imputation should be performed. A preliminary rule of thumb could be that the ratio of variables to cases with complete data should not go below 1 : 3.

Analysis 1.4. Comparison 1 Omega-3 PUFAs versus placebo, Outcome 4 Older Americans Resources and Services-Instrumental Activities of Daily Living (OARS-IADL) change scores (12 months' follow-up, PP analysis

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The family is of exceptional and lifelong importance to the health of adolescents. Family structure has been linked to children’s and adolescents’ health and well-being; a nuclear family has been shown to be indicative of better health outcomes as compared with a single-parent family or a step-family. Family climate is rarely included in studies on children’s and adolescents’ health and well-being, albeit findings have indicated it is importance. Using data from n = 6838 students aged 12–13 years from the German National Educational Panel Study, this study shows that stronger familial cohesion and better a parent-child relationship are associated with better self-rated health, higher life satisfaction, more prosocial behavior, and less problematic conduct, and that these associations are stronger than those for family structure. Surveys on young people’s health are encouraged to include family climate above and beyond family structure alone.

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