A model-based multiple imputation approach for analyzing sample data with non-detects is proposed. The imputation approach involves randomly generating observations below the detection limit using the detected sample values and then analyzing the data using complete sample techniques, along with suitable adjustments to account for the imputation. The method is described for the normal case and ...

We consider a distributed system where sensors make location parameter estimates using their observations. A central processor collects the local estimates and declares a nal estimate based on them. We present a simple study of the convergence properties of three structures where empirical mean and M-estimates are used in various combinations. It is shown that when occasional outliers exist, de...

An excess of lympho-haematopoietic (LH) cancers has been identi®ed in the Australian petroleum industry through the Health Watch surveillance programme. A nested case-control study is being conducted to investigate this excess. This paper describes the methods used to provide quantitative estimates of benzene exposure for each of the subjects in the case-control study. Job histories were compil...

BACKGROUND Health risks of using styrene to manufacture windblades for the green energy sector are unknown. METHODS Using data collected from 355 (73%) current windblade workers and regression analysis, we investigated associations between health outcomes and styrene exposure estimates derived from urinary styrene metabolites. RESULTS The median current styrene exposure was 53.6 mg/g creati...

conditional  methods  of adjustment  are often used to quantify  the effect  of the exposure on the outcome.  as  a  result,  the  stratums-specific  risk  ratio  estimates  are  reported  in  the  presence  of interaction   between   exposure  and  confounder(s)   in  the  literature,  even  if  the  target  of  the intervention on the exposure is the total population and the interaction itsel...

Exposure to environmental tobacco smoke (ETS) among individuals who have never smoked tobacco products has been well established as a risk factor for lung cancer. Most of the epidemiologic evidence for this association has come from studies of exposure to a spouse who smokes. Fewer studies have explicitly evaluated this risk relationship for workplace sources of ETS exposure. These are reviewed...

The purpose of this study is to investigate the potential impact of differing lung cancer risks in study populations on estimating population attributable fraction (PAF) from asbestos exposure. Studies were identified via a MEDLINE search up to September 2009 and from the reference lists of publications about asbestos exposure and lung cancer risk. Relative risk estimates were extracted from 16...

The current state of knowledge concerning mesothelioma risk estimates is reviewed. Estimates of the risk of mesothelioma exist for the commercial asbestos fiber types chrysotile, amosite and crocidolite. Data also exist on which to assess risks for winchite (sodic tremolite) and anthophyllite asbestos. Uncertainty in estimates is primarily related to limitations in measurements of exposure. Dif...

We propose a method for diagnosing confounding bias under a model that links a spatially and temporally varying exposure and health outcome. We decompose the association into orthogonal components, corresponding to distinct spatial and temporal scales of variation. If the model fully controls for confounding, the exposure effect estimates should be equal at the different temporal and spatial sc...

This paper examines recent risk assessments for benzene and observes a number of inconsistencies within the study and consistencies between studies that should effect the quantitative determination of the risk from benzene exposure. Comparisons across studies show that only acute myeloid leukemia (AML) is found to be consistently in excess with significant benzene exposure. The data from the Pl...