SAS and other popular statistical packages provide support for survey data with sampling weights. For example, PROC MEANS and PROC LOGISTIC in SAS have their counterparts PROC SURVEYMEANS and PROC SURVEYLOGISTIC to fa...SAS and other popular statistical packages provide support for survey data with sampling weights. For example, PROC MEANS and PROC LOGISTIC in SAS have their counterparts PROC SURVEYMEANS and PROC SURVEYLOGISTIC to facilitate analysis of data from complex survey studies. On the other hand, PROC MEANS and many other classic SAS procedures also provide an option for including weights and yield identical point estimates, but different standard errors (SEs), as their corresponding survey procedures. This paper takes an in-depth look at different types of weights and provides guidance on use of different SAS procedures.展开更多
Background: Malondialdehyde(MDA) is a candidate general marker of oxidative stress(OS). We sought to assess the relation of MDA to Gulf War illness(GWI) and to a variety of exposures.Methods: This is an observational ...Background: Malondialdehyde(MDA) is a candidate general marker of oxidative stress(OS). We sought to assess the relation of MDA to Gulf War illness(GWI) and to a variety of exposures.Methods: This is an observational study involving subjects from Southern California recruited from October 2011 to May 2014. MDA was assessed in 81 participants(41 GWI-cases, 40 controls). General and Gulf-specific exposures were elicited. MDA case–control comparison was restricted to 40 matched pairs. The potential association between MDA and exposures was assessed using regression analyses. Gulf-specific exposures were incorporated into a case-specific model.Results: Plasma MDA was significantly lower in GWI-cases than controls. Composite pesticide and fuel-solvent exposures negatively predicted MDA in the total sample, as well as in the analyses that included either GWI-cases or controls only. Self-reported exposure to organophosphate(OP) nerve gas was a strong predictor for lower MDA level in veterans with GWI.Conclusions: Past pesticide exposures predicted lower MDA in both veterans with GWI and in healthy controls.展开更多
文摘SAS and other popular statistical packages provide support for survey data with sampling weights. For example, PROC MEANS and PROC LOGISTIC in SAS have their counterparts PROC SURVEYMEANS and PROC SURVEYLOGISTIC to facilitate analysis of data from complex survey studies. On the other hand, PROC MEANS and many other classic SAS procedures also provide an option for including weights and yield identical point estimates, but different standard errors (SEs), as their corresponding survey procedures. This paper takes an in-depth look at different types of weights and provides guidance on use of different SAS procedures.
基金funded by the Depar tment of Defense Congressionally Directed Medical Research Program (GW093063)。
文摘Background: Malondialdehyde(MDA) is a candidate general marker of oxidative stress(OS). We sought to assess the relation of MDA to Gulf War illness(GWI) and to a variety of exposures.Methods: This is an observational study involving subjects from Southern California recruited from October 2011 to May 2014. MDA was assessed in 81 participants(41 GWI-cases, 40 controls). General and Gulf-specific exposures were elicited. MDA case–control comparison was restricted to 40 matched pairs. The potential association between MDA and exposures was assessed using regression analyses. Gulf-specific exposures were incorporated into a case-specific model.Results: Plasma MDA was significantly lower in GWI-cases than controls. Composite pesticide and fuel-solvent exposures negatively predicted MDA in the total sample, as well as in the analyses that included either GWI-cases or controls only. Self-reported exposure to organophosphate(OP) nerve gas was a strong predictor for lower MDA level in veterans with GWI.Conclusions: Past pesticide exposures predicted lower MDA in both veterans with GWI and in healthy controls.
