From Empirical Bayes to Full Bayes: Methods for Analysing Traffice Safety Data, October 25, 2004

Traffic safety engineers are among the early adopters of Bayesian statistical tools for analyzing crash data. As in many other areas of application, empirical Bayes methods were their first choice, perhaps because they represent an intuitively appealing, yet relatively easy to implement alternative to purely classical approaches. With the enormous progress in numerical methods made in recent years and with the availability of free, easy to use software that permits implementing a fully Bayesian approach, however, there is now ample justification to progress towards fully Bayesian analyses of crash data. The fully Bayesian approach, in particular as implemented via multi-level hierarchical models, has many advantages over the empirical Bayes approach. In a full Bayesian analysis, prior information and all available data are seamlessly integrated into posterior distributions on which practitioners can base their inferences. All uncertainties are thus accounted for in the analyses and there is no need to pre-process data to obtain Safety Performance Functions and other such prior estimates of the effect of covariates on the outcome of interest. In this slight, fully Bayesian methods may well be less costly to implement and may result in safety estimates with more realistic standard errors. In this manuscript, we present the full Bayesian approach to analyzing traffic safety data and focus on highlighting the differences between the empirical Bayes and the full Bayes approaches. We use an illustrative example to discuss a step-by-step Bayesian analysis of the data and to show some of the types of inferences that are possible within the full Bayesian framework.

From Empirical Bayes to Full Bayes: Methods for Analyzubg Traffic Safey Data, October 25, 2004

Traffic safety engineers are among the early adopters of Bayesian statistical tools for analyzing crash data. As in many other areas of application, empirical Bayes methods were their first choice, perhaps because they represent an intuitively appealing, yet relatively easy to implement alternative to purely classical approaches. With the enormous progress in numerical methods made in recent years and with the availability of free, easy to use software that permits implementing a fully Bayesian approach, however, there is now ample justification to progress towards fully Bayesian analyses of crash data. The fully Bayesian approach, in particular as implemented via multi-level hierarchical models, has many advantages over the empirical Bayes approach. In a full Bayesian analysis, prior information and all available data are seamlessly integrated into posterior distributions on which practitioners can base their inferences. All uncertainties are thus accounted for in the analyses and there is no need to pre-process data to obtain Safety Performance Functions and other such prior estimates of the effect of covariates on the outcome of interest. In this light, fully Bayesian methods may well be less costly to implement and may result in safety estimates with more realistic standard errors. In this manuscript, we present the full Bayesian approach to analyzing traffic safety data and focus on highlighting the differences between the empirical Bayes and the full Bayes approaches. We use an illustrative example to discuss a step-by-step Bayesian analysis of the data and to show some of the types of inferences that are possible within the full Bayesian framework.

Iowa Public Library Statistics Pocket Digest, 2008

The information in this digest comes from the FY08 Iowa Annual Public Library Survey. It reflects the activities of 522 of the 543 public libraries in Iowa. Full details may be found at http://www.statelibraryofiowa.org/ld/statistics. Information for the national rankings on pages 3 to 4 comes from Public Libraries in the United States: Fiscal Year 2006 by the Institute of Museum and Library Services, Washington D.C., December 2008. http://harvester.census.gov/imls/pubs/pls/pub_detail.asp?id=121#

2015-2019 Iowa Transportation Improvement Program

This document describes planned investments in Iowa's multimodal transportation system including aviation, transit, railroads, trails, and highways. A large part of funding available for highway programming comes from the federal government. Accurately estimating future federal funding levels is dependent on having a multiyear federal transportation authorization bill in place and having a sustainable and solvent federal Highway Trust Fund. The most recent federal authorization, Moving Ahead for Progress in the 21st Century (MAP-21), will expire September 30, 2014. At the same time that MAP-21 expires and absent Congressional action, the federal Highway Trust Fund will no longer be able to provide funding at current levels resulting in the full elimination of federal highway funding for new projects in federal fiscal year 2015. These two issues provide funding uncertainty with this program in fiscal years 2015 and beyond.

The Economic Potential of the Spergen Formation in Seven Southeastern Iowa Counties, HR-189, 1978

The middle Mississippian (Meramec Series) units include the Spergen Formation, the St. Louis Limestone and the Ste. Genevieve Formation which outcrop sporadically within a curvilinear subcrop band trending through southeastern and central Iowa. Studies of these units as they occur in Iowa have been cursory in the past, especially with regard to the lowermost occurring Meramecan unit, the Spergen Formation. The Spergen Formation, as it occurs in southeastern Iowa is being considered as a desirable concrete aggregate source. At present, the depth of occurrence, thickness variations and geographic extent are very poorly known and the nature of lithologic variation in Iowa is obscure. Due to a paucity of information of its thickness, extent and nature of rapid lateral facies variations, the full economic potential of the unit has not been realized in some areas of southeastern Iowa. This is especially disheartening in view of the decline of acceptable concrete aggregate source materials in southeastern Iowa. This report is an attempt to synthesize subsurface and surface data in order to present a more coherent picture of the depth, thickness and lithologic variations of the Spergen Formation. Recommendations have been made for the exploration of specific areas within the field area for future development of surface quarrying and subsurface mining operations where thickness, lithology and depth characteristics deem consideration. Due to the lack of adequate data points in some quadrants of the field area, some of the recommendations are drawn on rather tenuous grounds, but a concerted effort has been made to be conservative in these judgements.