Accuracy and repeatability of commercial geocoding

The authors estimated accuracy and repeatability of commercial geocoding to guide vendor selection in the Life Course Socioeconomic Status, Social Context and Cardiovascular Disease study (2001-2002). They submitted 1,032 participant addresses (97% in Maryland, Minnesota, Mississippi, or North Carolina) to vendor A twice over 9 months and measured repeatability as agreement between levels of address matching, discordance (%) between statistical tabulation areas, and median distance (d, in meters) and bearing (theta;, in degrees) between coordinates assigned on each occasion (H(o):Sigma(i)( = 1 -->) (n) [theta;(i) /n] = 180 degrees ). They also submitted 75 addresses of nearby air pollution monitors (77% urban/suburban; 69% residential/commercial) to vendors A and B and then measured accuracy by comparing vendor- and US Environmental Protection Agency (EPA)-assigned geocodes using the above measures. Repeatability of geocodes assigned by vendor A was high (kappa = 0.90; census block group discordance = 5%; d < 1 m; theta; = 177 degrees ). The match rate for EPA monitor addresses was higher for vendor B versus A (88% vs. 76%), but discordance at census block group, tract, and county levels also was, respectively, 1.4-, 1.9-, and 5.0-fold higher for vendor B. Moreover, coordinates assigned by vendor B were further from those assigned by the EPA (d = 212 m vs. 149 m; theta; = 131 degrees vs. 171 degrees ). These findings suggest that match rates, repeatability, and accuracy should be used to guide vendor selection.     

Comparing a single-stage geocoding method to a multi-stage geocoding method: how much and where do they disagree?

Background  

Geocoding methods vary among spatial epidemiology studies. Errors in the geocoding process and differential match rates may reduce study validity. We compared two geocoding methods using 8,157 Washington State addresses. The multi-stage geocoding method implemented by the state health department used a sequence of local and national reference files. The single-stage method used a single national reference file. For each address geocoded by both methods, we measured the distance between the locations assigned by each method. Area-level characteristics were collected from census data, and modeled as predictors of the discordance between geocoded address coordinates.     

Spatial error in geocoding physician location data from the AMA Physician Masterfile: implications for spatial accessibility analysis

The accuracy of geocoding hinges on the quality of address information that serves as input to the geocoding process; however errors associated with poor address quality are rarely studied. This paper examines spatial errors that arise due to incorrect address information with respect to physician location data in the United States. Studies of spatial accessibility to physicians in the U.S. typically rely on data from the American Medical Association's Physician Masterfile. These data are problematic because a substantial proportion of physicians only report a mailing address, which is often the physician's home (residential) location, rather than the address for the location where health care is provided. The incorrect geocoding of physicians' practice locations based on inappropriate address information results in a form of geocoding error that has not been widely analyzed. Using data for the Chicago metropolitan region, we analyze the extent and implications of geocoding error for measurement of spatial accessibility to primary care physicians. We geocode the locations of primary care physicians based on mailing addresses and office addresses. The spatial mismatch between the two is computed at the county, zip code and point location scales. Although mailing and office address locations are quite close for many physicians, they are far apart (>20 km) for a substantial minority. Kernel density estimation is used to characterize the spatial distribution of physicians based on office and mailing addresses and to identify areas of high spatial mismatch between the two. Errors are socially and geographically uneven, resulting in overestimation of physician supply in some high-income suburban communities, and underestimation in certain central city locations where health facilities are concentrated. The resulting errors affect local measures of spatial accessibility to primary care, biasing statistical analyses of the associations between spatial access to care and health outcomes.     

Influence of geocoding quality on environmental exposure assessment of children living near high traffic roads

Background  

The widespread availability of powerful geocoding tools in commercial GIS software and the interest in spatial analysis at the individual level have made address geocoding a widely employed technique in epidemiological studies. This study determined the effect of the positional error in street geocoding on the analysis of traffic-related air pollution on children.     

Local indicators of geocoding accuracy (LIGA): theory and application

Background  

Although sources of positional error in geographic locations (e.g. geocoding error) used for describing and modeling spatial patterns are widely acknowledged, research on how such error impacts the statistical results has been limited. In this paper we explore techniques for quantifying the perturbability of spatial weights to different specifications of positional error.     

Accuracy of a PDA-based dietary assessment program

OBJECTIVE: Study objectives were to assess the accuracy of a food record delivered on a personal digital assistant (PDA) and to examine sources of error from the PDA-based food record. METHODS: Thirty-nine adults recruited with a newspaper advertisement were trained to record food intake using DietMatePro, a dietary assessment program delivered on a PDA. After 3 d of use, subjects returned for a follow-up visit in which a 24-h recall was conducted. Subjects also were timed while recording an observed, weighed lunch. Recalled and actual food intakes were compared with estimates recorded by the subjects when using the PDA. Paired sample t tests and Pearson's correlations assessed means and measurements of association between DietMatePro data compared with the 24-h recall data and observed meal data. Bland-Altman plots were used to assess bias in food recording. Sources of error were quantified by using calories as the unit for comparison. RESULTS: There were no significant differences in daily totals for calories and macronutrients between DietMatePro data and comparison measurements. Pearson's correlations of associations between DietMatePro data and the comparison measurement ranged from 0.505 to 0.797 (P < 0.005, n = 28) for the 24-h recall and from 0.419 to 0.786 (P < 0.005, n = 33) for the observed lunch, depending on the nutrient measured. The largest source of absolute error in caloric estimation was attributable to portion size estimation error (49%). CONCLUSIONS: DietMatePro, a PDA-based dietary assessment program, provides a method of assessing energy and macronutrient intakes comparable to the 24-h recall in samples lacking dietary restrictions.     

Accuracy of self-reported body weight: Stepped Approach Model component assessment

This study was conducted to investigate innovative solutions to a measurement problem pertaining to self-reported body weight data as a key component of the Stepped Approach Model (SAM) of service delivery. Subjects (n = 223) were randomly assigned to one of two conditions: Informed Group (of self-report and weight measurement) + six body weighing habit items (IG, n = 113) and Uninformed Group (of self-report and weight measurement) + one body weight item (UG, n = 110). A t-test indicated that IG subjects reported significantly more accurately, t(194) = 2.99, P = 0.002, and with significantly less variability than UG subjects, F(109,112) = 1.95, P < 0.0005. A multiple regression of absolute difference weight (observed--self-reported weight) on observed weight revealed consistent accuracy across the weight range for IG subjects, whereas UG subjects' accuracy decreased as body weight increased. The slope of the IG did not significantly differ from 0, t(218) = 1.44, P = 0.150, but did significantly differ from the slope of the UG, t(218) = 2.78, P = 0.006. The following conclusions are noted when IG conditions are used: (1) a three-component strategy designed for maximum effect size results in accurate reporting across the entire weight range, (2) self-reported body weights under prescribed conditions can be used as valid 'proxies' for observed measurements, and (3) SAM proponents can rely on the validity of self-report body weight as a credible basis for decisions about changing intervention steps and evaluating intervention efficacy.     

Positional accuracy of two methods of geocoding

BACKGROUND: Geocoding is often used in epidemiologic studies to map residences with geographic information systems (GIS). The accuracy of the method is usually not determined. METHODS: We collected global positioning system (GPS) measurements at homes in a case-control study of non-Hodgkin lymphoma in Iowa. We geocoded the addresses by 2 methods: (1) in-house, using ArcView 3.2 software and the U.S. Census Bureau TIGER 2000 street database; and (2) automated geocoding by a commercial firm. We calculated the distance between the geocoded and GPS location (positional error) overall and separately for homes within towns and outside (rural). We evaluated the error in classifying homes with respect to their proximity to crop fields. RESULTS: Overall, the majority of homes were geocoded with positional errors of less than 100 m by both methods (ArcView/TIGER 2000, median = 62 m [interquartile range = 39-103]; commercial firm, median = 61 m [interquartile range = 35-137]). For town residences, the percent geocoded with errors of 相似文献   

Monitoring socioeconomic inequalities in sexually transmitted infections,tuberculosis, and violence: geocoding and choice of area-based socioeconomic measures--the public health disparities geocoding project (US)

OBJECTIVES: To determine which area-based socioeconomic measures, at which level of geography, are suitable for monitoring socioeconomic inequalities in sexually transmitted infections (STIs), tuberculosis (TB), and violence in the United States. METHODS: Cross-sectional analysis of public health surveillance data, geocoded and linked to area-based socioeconomic measures generated from 1990 census tract, block group, and ZIP Code data. We included all incident cases among residents of either Massachusetts (MA; 1990 population = 6016425) or Rhode Island (RI; 1990 population = 1003464) for: STIs (MA: 1994-1998, n = 26535 chlamydia, 7464 gonorrhea, 2619 syphilis; RI: 1994-1996, n = 4473 chlamydia, 1256 gonorrhea, 305 syphilis); TB (MA: 1993-1998, n = 1793; RI: 1985-1994, n = 576), and non-fatal weapons related injuries (MA: 1995-1997, n = 6628). RESULTS: Analyses indicated that: (a). block group and tract socioeconomic measures performed similarly within and across both states, with results more variable for the ZIP Code level measures; (b). measures of economic deprivation consistently detected the steepest socioeconomic gradients, considered across all outcomes (incidence rate ratios on the order of 10 or higher for syphilis, gonorrhea, and non-fatal intentional weapons-related injuries, and 7 or higher for chlamydia and TB); and (c). results were similar for categories generated by quintiles and by a priori categorical cut-points. CONCLUSIONS: Supplementing U.S. public health surveillance systems with census tract or block group area-based socioeconomic measures of economic deprivation could greatly enhance monitoring and analysis of social inequalities in health in the United States.     

Positional error in automated geocoding of residential addresses

Background  

Public health applications using geographic information system (GIS) technology are steadily increasing. Many of these rely on the ability to locate where people live with respect to areas of exposure from environmental contaminants. Automated geocoding is a method used to assign geographic coordinates to an individual based on their street address. This method often relies on street centerline files as a geographic reference. Such a process introduces positional error in the geocoded point. Our study evaluated the positional error caused during automated geocoding of residential addresses and how this error varies between population densities. We also evaluated an alternative method of geocoding using residential property parcel data.     

An assessment of the cord blood:maternal blood methylmercury ratio: implications for risk assessment

In the current U.S. Environmental Protection Agency reference dose (RfD) for methylmercury, the one-compartment pharmacokinetic model is used to convert fetal cord blood mercury (Hg) concentration to a maternal intake dose. This requires a ratio relating cord blood Hg concentration to maternal blood Hg concentration. No formal analysis of either the central tendency or variability of this ratio has been done. This variability contributes to the overall variability in the dose estimate. A ratio of 1.0 is implicitly used in the model, but an uncertainty factor adjustment is applied to the central tendency estimate of dose to address variability in that estimate. Thus, incorporation of the cord:maternal ratio and its variability into the estimate of intake dose could result in a significant change in the value of the RfD. We analyzed studies providing data on the cord:maternal blood Hg ratio and conducted a Monte Carlo-based meta-analysis of 10 studies meeting all inclusion criteria to generate a comprehensive estimate of the central tendency and variability of the ratio. This analysis results in a recommended central tendency estimate of 1.7, a coefficient of variation of 0.56, and a 95th percentile of 3.4. By analogy to the impact of the similar hair:blood Hg ratio on the overall variability in the dose estimate, incorporation of the cord:maternal ratio may support a 3-fold uncertainty factor adjustment to the central tendency estimate of dose to account for pharmacokinetic variability. Whether the information generated in this analysis is sufficient to warrant a revision to the RfD will depend on the outcome of a comprehensive reanalysis of the entire one-compartment model. We are currently engaged in such an analysis.     

Community-oriented primary care: critical assessment and implications for resident education

BACKGROUND: Community-oriented primary care (COPC) is a systematic approach to health care based on principles derived from epidemiology, primary care, preventive medicine, and health promotion that has been shown to have positive health benefits for communities in the United States and worldwide. METHODS: MEDLINE was searched using the key phrase "community-oriented primary care." Other sources of information were books and other documents. RESULTS AND CONCLUSIONS: Because of lack of predictable reimbursement for COPC services and difficulties encountered incorporating COPC in medical and residency curricula, widespread application of COPC has not occurred. Recent trends in public health initiatives, managed health care, and information technology provide an environment ripe for application of COPC in medical practice. Also, recent recommendations made by the Strategic Planning Working Group of the Academic Family Medicine Organizations and the Association of Family Practice Residency Directors regarding specific community competencies for residency training have direct bearing on COPC and family medicine educators. These trends and recommendations, properly configured, will produce a medical training and practice environment conducive to COPC.     

Considering the interdependence of clinical performance: implications for assessment and entrustment

Introduction

Our ability to assess independent trainee performance is a key element of competency‐based medical education (CBME). In workplace‐based clinical settings, however, the performance of a trainee can be deeply entangled with others on the team. This presents a fundamental challenge, given the need to assess and entrust trainees based on the evolution of their independent clinical performance. The purpose of this study, therefore, was to understand what faculty members and senior postgraduate trainees believe constitutes independent performance in a variety of clinical specialty contexts.

Methods

Following constructivist grounded theory, and using both purposive and theoretical sampling, we conducted individual interviews with 11 clinical teaching faculty members and 10 senior trainees (postgraduate year 4/5) across 12 postgraduate specialties. Constant comparative inductive analysis was conducted. Return of findings was also carried out using one‐to‐one sessions with key informants and public presentations.

Results

Although some independent performances were described, participants spoke mostly about the exceptions to and disclaimers about these, elaborating their sense of the interdependence of trainee performances. Our analysis of these interdependence patterns identified multiple configurations of coupling, with the dominant being coupling of trainee and supervisor performance. We consider how the concept of coupling could advance workplace‐based assessment efforts by supporting models that account for the collective dimensions of clinical performance.

Conclusion

These findings call into question the assumption of independent performance, and offer an important step toward measuring coupled performance. An understanding of coupling can help both to better distinguish independent and interdependent performances, and to consider revising workplace‐based assessment approaches for CBME.     

Malnutrition and dysfunctional mother-child feeding interactions: clinical assessment and research implications

OBJECTIVES: To evaluate the effects of age and the presence of feeding pathologies on the relational modes during meals in a sample of mother-child pairs (n = 333), comparing groups of children in the first three years of life with normal development (ND-group, n = 211) and clinical groups of children who presented a diagnosis of feeding disorder and failure to thrive (FD-group, n = 122), and to show an association between specific symptomatic characteristics of the mother, of the child and the dysfunctional modes of their relationship during meals in a subgroup of mother-child pairs (n = 50), selected at random from the total clinical sample and paired with a control group chosen for this study. METHODS: All mother-child pairs in the sample were observed in twenty-minute video-recordings during a meal, using the procedure of the Feeding Scale in the Italian version. A subgroup of mothers, selected at random from the total clinical sample, and paired with a control group, were given two self-reporting instruments for the evaluation of their psychological symptom status: the Eating Attitude Test and the Symptom Checklist-90-Revised, as well as two instruments for the evaluation of the infant temperament and emotional/behavioral functioning: the Baby and Toddler Behavior Questionnaires (from 1 to 18 months) and the Child Behavior Checklist 1-1/2--5 (from 18 to 36 months). RESULTS: Analysis of variance showed that the FD-group present interactional dysfunctional patterns during feeding and raise higher scores in symptomatic characteristics both of the mother and of the child, compared to ND-group. A set of correlation analyses (Pearson coefficients) showed an association among specific symptomatic characteristics of the mothers (dysfunctional eating attitudes, anxiety, depression, hostility), of their children (in particular, anxiety/depression, somatic complaints and aggressive behavior) and of their dysfunctional relational modes during feeding (p < 0.05). CONCLUSIONS: Our study confirms that analysis of the individual characteristics of the child, of the mother and of their relationship during the development of feeding patterns in the first three years of the child's life is extremely important in the clinical assessment of early feeding disorders, in order to establish a valid diagnostic methodology and formulate strategies for targeted and effective intervention. Furthermore, the results emphasize the clinical utility of our research in early identification of infants and toddlers at risk for feeding problems.     

Exposure of flight attendants to pyrethroid insecticides on commercial flights: urinary metabolite levels and implications

Pyrethroid insecticides have been used for disinsection of commercial aircrafts. However, little is known about the pyrethroids exposure of flight attendants. The objective of the study was to assess pyrethroids exposure of flight attendants working on commercial aircrafts through monitoring the urinary pyrethroids metabolite levels. Eighty four urine samples were collected from 28 flight attendants, 18-65 years of age, with seventeen working on planes that were non-disinsected, and eleven working on planes that had been disinsected. Five urinary metabolites of pyrethroids were measured using gas chromatographic-mass spectrometric method: 3-phenoxybenzoic acid (3-PBA), cis-/trans-3-(2,2-Dichlorovinyl)-2,2-dimethylcyclo-propane carboxylic acid (cis-/trans-Cl2CA), cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclo-propane-1-carboxylic acid (cis-Br2CA) and 4-fluoro-3-phenoxybenzoic acid (4F-3-PBA). Flight attendants working on disinsected planes had significantly higher urinary levels of 3-PBA, cis- and trans-Cl2CA in pre, post- and 24-h-post flight samples than those on planes which did not report having been disinsected. Urinary levels of cis-Br2CA and 4F-3-PBA did not show significant differences between the two groups. Flight attendants working on international flights connected to Australia had higher urinary levels of 3-PBA, cis- and trans-Cl2CA than those on either domestic and other international flights flying among Asia, Europe and North America. Post-disinsection duration (number of days from disinsection date to flight date) was the most significant factor affecting the urinary pyrethroid metabolites levels of 3-PBA, cis- and trans-Cl2CA of the group flying on disinsected aircraft. It was concluded that working on commercial aircraft disinsected by pyrethroids resulted in elevated body burdens of 3-PBA, cis- and trans-Cl2CA.