Copyright (c) 2009 All rights reserved. http://works.bepress.com/tbrachet Recent documents in Tanguy Brachet en-us Sun, 31 May 2009 12:39:57 PDT 3600 http://works.bepress.com/tbrachet/7 http://works.bepress.com/tbrachet/7 Wed, 04 Feb 2009 20:38:04 PST Objectives. The prehospital management of trauma patients remains controversial. Little is known about the time each procedure contributes to the on-scene duration, and this information would be helpful in prioritizing which procedures to perform in the prehospital setting. We sought to estimate the contribution of procedures to on-scene duration focusing on intubation and establishment of intravenous (IV) access. Methods. Data were provided by the Office of Emergency Planning and Response at the Mississippi Department of Health. Real-time prehospital patient-level data are collected by emergency medical services (EMS) providers for all 9-1-1 calls statewide. Linear regression was performed to determine the overall additional time for an average procedure and to calculate marginal increases in on-scene time associated with the establishment of IV access and with endotracheal intubation. Analyses were performed using Stata 9. Results. During 2001-2005, 192,055 prehospital runs were made for trauma patients. 121,495 (63%) included prehospital procedures. Average on-scene duration for those runs was 15:24 (minutes:seconds). On average, each procedure was associated with an addition of 1 minute to the on-scene duration (95% confidence interval [CI]: 58-62 seconds).Ascene involving the establishment of IV access was 5:04 longer, while one involving tracheal intubation was 2:36 longer. Conclusions. We estimate the marginal increase in on-scene duration associated with the performance of an average procedure, establishment of IV access, and endotracheal intubation. There are policy and planning implications for the time trade-off of prehospital procedures, especially discretionary ones. Brendan G. Carr Emergency Medical Services http://works.bepress.com/tbrachet/6 http://works.bepress.com/tbrachet/6 Wed, 04 Feb 2009 20:25:27 PST Tanguy Brachet http://works.bepress.com/tbrachet/5 http://works.bepress.com/tbrachet/5 Wed, 04 Feb 2009 14:57:44 PST Studies of organizational learning and forgetting identify potential channels through which the firm's production experience is lost. While the ability to distinguish between these channels has implications for efficient resource allocation within the firm, to date, their relative importance has largely been ignored. This paper develops a framework for eliciting the contributions of the two most salient channels, labor turnover and human capital depreciation, to organizational forgetting. We apply our framework to a novel and detailed dataset of ambulance companies and their workforce. We find evidence of organizational forgetting, which results from sizable skill decay and turnover effects, with the latter having twice the magnitude of the former. In addition, we evaluate productivity spillovers in experience as well as the contribution of production inactivity and the scope of tasks to individual‐level skill decay. Tanguy Brachet Emergency Medical Services Organizational Forgetting http://works.bepress.com/tbrachet/3 http://works.bepress.com/tbrachet/3 Mon, 02 Feb 2009 22:57:01 PST Objectives: To examine the strength of the volume-outcome relationship among paramedics, a group of providers that has not been previously studied in this context. By identifying the effects of individual learning on performance, we also assess the value of paramedics' retention. The pre-hospital emergency medical services (EMS) setting allows us to interpret any volume-outcome relationship as learning-by-doing, uncontaminated by reputation-based referrals since ambulance units are dispatched based on proximity. Data Sources: Incident-level EMS data spanning 1991 to 2005 from the Mississippi Emergency Medical Services Information System (MEMSIS) collected by the Mississippi Department of Health. Research Design: Using linear and quantile methods with and without provider fixed effects, we estimate the relationship between experience accumulation and performance using the universe of trauma incidents involving injured patients (including motor vehicle crashes, falls, stabbings and shootings). Principal Findings: We find that greater individual volume is robustly related to improved performance. In addition, we find that the benefit of learning operates through both recent and past experiences, accrues differentially across tenure groups, and operates on both mean performance and the upper quantiles of the performance distribution. Conclusions: Persistent past and current volume effects suggest that policy and managerial implications in EMS should be directed at retention efforts to take advantage of individual learning by paramedics. Guy David Emergency Medical Services http://works.bepress.com/tbrachet/2 http://works.bepress.com/tbrachet/2 Thu, 12 Apr 2007 10:30:40 PDT Since SAS doesn't offer a 2SLS procedure that allows for clustered standard errors, this macro develops an equivalent algorithm based on SAS's available procedures. The steps are as follows: [1] estimate the first stage by OLS and save the endogenous variable's predicted values (PROC REG); [2] estimate the structural equation as usual and save the 2SLS residuals (PROC SYSLIN); [3] merge the dataset containing the first stage predictions with that containing the 2SLS residuals; [4] regress the 2SLS residuals on the 1st stage predicted values and all other exogenous variables, clustering the standard errors by the cluster variable (PROC SURVEYREG). The standard errors reported in step [4] are the clustered 2SLS standard errors. Tanguy Brachet Software http://works.bepress.com/tbrachet/1 http://works.bepress.com/tbrachet/1 Sat, 25 Nov 2006 22:50:59 PST Identifying the causal effect of prenatal maternal smoking on infant health is complicated by unobservable maternal characteristics and behaviors which are plausibly related both to birth outcomes and to a mother's decisions to smoke. Previous economic studies have addressed this omitted variables problem with the use of instrumental variables (IV). However, with (noisy) self-reported data on maternal tobacco use, misreporting can enduce more severe biases in the IV estimates than those resulting from the endogeneity problem which instrumental variables were originally invoked to eliminate. In this paper, I propose a method of estimating the effect of maternal smoking on birth outcomes that addresses both the endogeneity and measurement error problems. When a binary variable is misclassified, the measurement error is necessarily negatively correlated with the truth. This observation has important implications for an IV framework in which the endogenous variable is a potentially mismeasured binary variable. Ignoring misclassification leads to attenuation in the first stage coefficients and, by extension, to inflated second stage estimates of the causal effects of interest. The GMM approach I propose is based on recently developed parametric methods for misclassified binary dependent variables that allow me to recover consistent estimates of the second stage coefficients, as well as of the misclassification probabilities.Using this method, I then re-analyze the relationship between infant health and maternal smoking. When state cigarette excise taxes are used as an instrument for tobacco use without accounting for measurement error in self-reported smoking, the conventional IV estimate of the birth weight cost of smoking is only slightly smaller in magnitude than its OLS counterpart for whites, but substantially larger for African Americans: of the order of one third of the average infant's birth weight. Accounting for misclassification yields causal estimates that are considerably smaller in absolute value and more consistent with experimental estimates. The results also suggests that the effect is heterogeneous across races: the birth weight loss due to smoking is around 200 grams for whites and roughly twice that amount for African Americans. Tanguy Brachet Infant Health Measurement Error