Evaluation of the use of bias factors with water monitoring data.

Aquatic exposure assessments using surface water quality monitoring data are often challenged by missing extreme concentrations if sampling frequency is less than daily. A bias factor method has been previously proposed to address this concern for peak concentrations, where a bias factor is a multiplicative quantity to upwardly adjust estimates so that the true value is exceeded 95% of the time. In other words, bias factors are statistically protective adjustments.

Flow-covariate prediction of stream pesticide concentrations.

Potential peak functions (e.g., maximum rolling averages over a given duration) of annual pesticide concentrations in the aquatic environment are important exposure parameters (or target quantities) for ecological risk assessments.

Kriging Models Predicting Atrazine Concentrations in Surface Water Draining Agricultural Watersheds.

The performance of kriging methods in predicting maximum m-day (m = 1, 7, 14, or 30) rolling averages of atrazine concentrations in 42 site-years of Midwest Corn Belt watersheds under two systematic sampling designs (sampling every 7 or 14 d) was examined. Daily atrazine monitoring data obtained from the Atrazine Ecological Monitoring Program in the Corn Belt region (2009-2014) were used in the evaluation. Both ordinary and universal kriging methods were considered, with the covariate for universal kriging derived from the deterministic Pesticide Root Zone Model (PRZM).

Estimating the prevalence of any impairing childhood mental disorder in the national health interview survey.

This study investigates whether the six-item Strengths and Difficulties Questionnaire SDQ (five symptoms and one impact item) included in the National Health Interview Survey (NHIS) can be used to construct models that accurately estimate the prevalence of any impairing mental disorder among children 4-17 years old as measured by a shortened Child/Adolescent or Preschool Age Psychiatric Assessment (CAPA or PAPA). A subsample of 217 NHIS respondents completed a follow-up CAPA or PAPA interview. Logistic regression models were developed to model presence of any child mental disorder with impairment (MDI) or with severe impairment (MDSI).

Peak centiles of chlorpyrifos surface-water concentrations in the NAWQA and NASQAN programs.

We provide upper bound estimates for peak centiles of surface water chlorpyrifos concentration readings within spatial, temporal, and land-use domains of the United States Geological Survey (USGS) National Water-Quality Assessment (NAWQA) and National Stream Quality Accounting Network (NASQAN) programs. These datasets have large overall sample sizes but variable sampling frequencies and, for chlorpyrifos, extremely high levels of non-detections. Point and interval estimates are provided for the 90th, 95th, 99th, and the 99.

The National Survey on Drug Use and Health Mental Health Surveillance Study: calibration analysis.

The Mental Health Surveillance Study (MHSS) is an ongoing initiative by the Substance Abuse and Mental Health Services Administration to develop and implement methods for measuring the prevalence of serious mental illness (SMI) among adults in the USA. The 2008 MHSS used data from clinical interviews administered to a sub-sample of respondents to calibrate mental health screening scale data from the National Survey on Drug Use and Health (NSDUH) for estimating the prevalence of SMI in the full NSDUH sample. The mental health scales included the K6 screening scale of psychological distress (administered to all respondents) along with two measures of functional impairment (each administered to a random half-sample of respondents): the World Health Organization Disability Assessment Schedule (WHODAS) and the Sheehan Disability Scale (SDS).

The National Survey on Drug Use and Health Mental Health Surveillance Study: calibration study design and field procedures.

The Mental Health Surveillance Study (MHSS) is an ongoing initiative by the Substance Abuse and Mental Health Services Administration (SAMHSA) to monitor the prevalence of serious mental illness (SMI) among adults in the USA. In 2008, the MHSS used data from clinical interviews to calibrate mental health data from the National Survey on Drug Use and Health (NSDUH) for estimating the prevalence of SMI based on the full NSDUH sample. The clinical interview used was the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders 4th edition (DSM-IV; SCID).

Estimated drug use based on direct questioning and open-ended questions: responses in the 2006 National Survey on Drug Use and Health.

Substance use surveys may use open-ended items to supplement questions about specific drugs and obtain more exhaustive information on illicit drug use. However these questions are likely to underestimate the prevalence of use of specific drugs. Little is known about the extent of such underestimation or the groups most prone to under-reporting.

Statistical tools for determining appropriate selection of regression models for analysis of environmental fate datasets.

Background: In the NAFTA regulatory community, a currently consistent methodology used to estimate dissipation times for environmental fate data is not applied.

Results: This work demonstrates through a case study that the inappropriate use of pseudo-first-order regression models can result in inaccurate estimates of soil degradation rates, and it proposes some statistical tools that can be used to identify an appropriate statistical model to fit a particular environmental fate dataset. Diagnostic procedures have been proposed to identify the appropriate scale, and statistical testing procedures have been proposed to select the appropriate model within that scale.