Extant‐only comparative methods fail to recover the disparity preserved in the bird fossil record

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/113721/1/evo12738.pd

Hypothesis testing near singularities and boundaries

The likelihood ratio statistic, with its asymptotic $\chi^2$ distribution at regular model points, is often used for hypothesis testing. At model singularities and boundaries, however, the asymptotic distribution may not be $\chi^2$, as highlighted by recent work of Drton. Indeed, poor behavior of a $\chi^2$ for testing near singularities and boundaries is apparent in simulations, and can lead to conservative or anti-conservative tests. Here we develop a new distribution designed for use in hypothesis testing near singularities and boundaries, which asymptotically agrees with that of the likelihood ratio statistic. For two example trinomial models, arising in the context of inference of evolutionary trees, we show the new distributions outperform a $\chi^2$.Comment: 32 pages, 12 figure

Early CRT monitoring using time-domain optical coherence tomography does not add to visual acuity for predicting visual loss in patients with central retinal vein occlusion treated with intravitreal ranibizumab:A secondary analysis of trial data

Our primary purpose was to assess the clinical (predictive) validity of central retinal thickness (CRT) and best corrected visual acuity (BCVA) at 1 week and 1 month after starting treatment with ranibizumab for central retinal vein occlusion. The authors also assessed detectability of response to treatment

A generalized AIC for models with singularities and boundaries

The Akaike information criterion (AIC) is a common tool for model selection. It is frequently used in violation of regularity conditions at parameter space singularities and boundaries. The expected AIC is generally not asymptotically equivalent to its target at singularities and boundaries, and convergence to the target at nearby parameter points may be slow. We develop a generalized AIC for candidate models with or without singularities and boundaries. We show that the expectation of this generalized form converges everywhere in the parameter space, and its convergence can be faster than that of the AIC. We illustrate the generalized AIC on example models from phylogenomics, showing that it can outperform the AIC and gives rise to an interpolated effective number of model parameters, which can differ substantially from the number of parameters near singularities and boundaries. We outline methods for estimating the often unknown generating parameter and bias correction term of the generalized AIC.Comment: 21 pages, 5 figure

Auto-Enrollment Retirement Plans for the People: Choices and Outcomes in OregonSaves

Oregon recently launched an automatic-enrollment retirement savings program for private sector workers who lack access to other workplace retirement plans. We analyze participation choices, account balances, and inflow/outflow data using administrative records between August 2018 and April 2020. Within the small to mid-sized firms served by OregonSaves, estimated average after-tax earnings are low ($2,365 per month) and turnover rates are high (38.2$51.1 million in total assets. The average balance is $754, but there is considerable dispersion, with younger workers accumulating the fewest assets due to higher rates of job turnover. Overall, we conclude that OregonSaves has meaningfully increased employee savings by reducing search costs. The 34.3% of workers with positive account balances in April 2020 is comparable to the marginal increase in participation at larger firms in the private sector. Nevertheless, there are significant constraints to the savings that auto-enrollment savings plans can achieve when provided to workers in industries and firms with low wages, volatile wages, and high turnover. Our evidence suggests that employees who are opting out of OregonSaves are often doing so for rational reasons

Phylogenetic stability, tree shape, and character compatibility: a case study using early tetrapods

Phylogenetic tree shape varies as the evolutionary processes affecting a clade change over time. In this study, we examined an empirical phylogeny of fossil tetrapods during several time intervals, and studied how temporal constraints manifested in patterns of tree imbalance and character change. The results indicate that the impact of temporal constraints on tree shape is minimal and highlights the stability through time of the reference tetrapod phylogeny. Unexpected values of imbalance for Mississippian and Pennsylvanian time slices strongly support the hypothesis that the Carboniferous was a period of explosive tetrapod radiation. Several significant diversification shifts take place in the Mississippian and underpin increased terrestrialization among the earliest limbed vertebrates. Character incompatibility is relatively high at the beginning of tetrapod history, but quickly decreases to a relatively stable lower level, relative to a null distribution based on constant rates of character change. This implies that basal tetrapods had high, but declining, rates of homoplasy early in their evolutionary history, although the origin of Lissamphibia is an exception to this trend. The time slice approach is a powerful method of phylogenetic analysis and a useful tool for assessing the impact of combining extinct and extant taxa in phylogenetic analyses of large and speciose clades

Minimum-Cost Coverage of Point Sets by Disks

We consider a class of geometric facility location problems in which the goal is to determine a set X of disks given by their centers (t_j) and radii (r_j) that cover a given set of demand points Y in the plane at the smallest possible cost. We consider cost functions of the form sum_j f(r_j), where f(r)=r^alpha is the cost of transmission to radius r. Special cases arise for alpha=1 (sum of radii) and alpha=2 (total area); power consumption models in wireless network design often use an exponent alpha>2. Different scenarios arise according to possible restrictions on the transmission centers t_j, which may be constrained to belong to a given discrete set or to lie on a line, etc. We obtain several new results, including (a) exact and approximation algorithms for selecting transmission points t_j on a given line in order to cover demand points Y in the plane; (b) approximation algorithms (and an algebraic intractability result) for selecting an optimal line on which to place transmission points to cover Y; (c) a proof of NP-hardness for a discrete set of transmission points in the plane and any fixed alpha>1; and (d) a polynomial-time approximation scheme for the problem of computing a minimum cost covering tour (MCCT), in which the total cost is a linear combination of the transmission cost for the set of disks and the length of a tour/path that connects the centers of the disks.Comment: 10 pages, 4 figures, Latex, to appear in ACM Symposium on Computational Geometry 200

Autonomy found: Estimating the local benefit from tourism in SIDS – the Case of Cape Verde

Tourism is an unusually important economic sector for the Small Island Development States (SIDS). Islands are the second most visited destinations after historic cities. The SIDS tourism is usually dependent on foreign investment and in the form of All-Inclusive (AI) system. Few studies have evaluated the economic impact of tourism on the economic development and/or poverty reduction of a SID using macro level data. And little research has used micro/firm level data to investigate the impact of tourism on the local economy of SIDS. This paper aims to evaluate the local benefits made from the development of tourism in SIDS, in particular the contribution of AI accommodation using the case of Cape Verde. It makes two main contributions: it makes the first attempt to use microeconomic data at the company level to examine the contribution of tourism in SIDS; it uses empirical data to examine the impacts of AI accommodation on the local economy. A semi-structured hotel questionnaire was applied to 13 accommodation managers and hotel owners, from small guest-houses to large 500 room All-Inclusive resorts in Sal, Boa Vista, Fogo, and Santo Antão. The results indicate that for destinations at an early stage in their development, large-scale AIs may be the most effective way to achieve the growth of tourism to the point that a critical mass is achieved