Estimating Fixed Effects: Perfect Prediction and Bias in Binary Response Panel Models, with an Application to the Hospital Readmissions Reduction Program

The maximum likelihood estimator for the regression coefficients, β, in a panel binary response model with fixed effects can be severely biased if N is large and T is small, a consequence of the incidental parameters problem. This has led to the development of conditional maximum likelihood estimators and, more recently, to estimators that remove the O(T–1) bias in β^. We add to this literature in two important ways. First, we focus on estimation of the fixed effects proper, as these have become increasingly important in applied work. Second, we build on a bias-reduction approach originally developed by Kosmidis and Firth (2009) for cross-section data, and show that in contrast to other proposals, the new estimator ensures finiteness of the fixed effects even in the absence of within-unit variation in the outcome. Results from a simulation study document favourable small sample properties. In an application to hospital data on patient readmission rates under the 2010 Affo

Understanding rock materials exploitation along the Ancient Appia route by means of integrated geoarchaeological and microstratigraphic analyses

A comparison between Mesozoic carbonates and ancient Roman ashlars was performed by microstratigraphic analyses to complete a geoarcheological characterization of a rock cave system featuring the Ancient Appia route where it crosses the Aurunci ridge along the San Andrea Valley, between the modern villages of Fondi and Itri (southern Latium). This research is part of a FIRB project led by the CNR-ITABC in collaboration with the Second University of Naples - Department of Literature and Cultural Heritage, to which other Universities, CNR Research Institutes and private societies have occasionally collaborated. The understanding of the anthropogenic landscape modifications required a multidisciplinary approach. Results show the preferential use of coarsegrained Aptian limestones on the northern part of the road tract and Cenomanian-Turonian limestones in correspondence of the southern zone

Overall survival in IGP model subgroups.

<p>A. Overall survival by cytogenetics and mutational profiles. Among patients with intermediate cytogenetics, three-year overall survival was 59% for those with favorable mutational profiles (A), 33% for those with intermediate mutational profiles (B), 51% for those who were <i>FLT3-</i>ITD negative with high-risk mutations (C) and 11% for those who were <i>FLT3-</i>ITD positive with high-risk mutations (D). Three-year overall survival was 77% among patients with favorable cytogenetics (favorable) and 21% among patients with unfavorable cytogenetics (unfavorable). B. Overall survival among patients with favorable mutational profiles. The overall survival curve for patients with intermediate cytogenetics and mutant <i>NPM1</i> plus mutant <i>IDH1</i> or <i>IDH2</i> was similar to the survival curve for patients with favorable cytogenetics (adjusted p = 0.697) and different from the survival curve for patients in the intermediate IGP risk group (adjusted p = 0.028). C. Overall survival among patients with <i>FLT3-</i>ITD negative AML and high-risk mutations. The overall survival curve for patients with <i>FLT3</i>-ITD negative (<i>FLT3-</i>ITD-) AML and co-occurring high-risk mutations (<i>TET2</i>, <i>ASXL1</i> and/or <i>PHF6</i>) was not significantly different from the survival curves for patients with unfavorable cytogenetics or patients with intermediate IGP risk (adjusted p = 0.111 and p = 0.919, respectively). D. Overall survival among patients with <i>FLT3</i>-ITD positive AML and high-risk mutations. The overall survival curve for patients with <i>FLT3</i>-ITD positive (<i>FLT3</i>-ITD+) AML and co-occurring high-risk mutations (trisomy 8, <i>TET2</i> and/or <i>DNMT3A</i>) was similar to the survival curve for patients with unfavorable cytogenetics (adjusted p = 0.793) and different from the survival curve for patients in the intermediate IGP risk group (adjusted p = 0.022).</p