Bayesian matching of unlabeled marked point sets using random fields, with an application to molecular alignment

Statistical methodology is proposed for comparing unlabeled marked point sets, with an application to aligning steroid molecules in chemoinformatics. Methods from statistical shape analysis are combined with techniques for predicting random fields in spatial statistics in order to define a suitable measure of similarity between two marked point sets. Bayesian modeling of the predicted field overlap between pairs of point sets is proposed, and posterior inference of the alignment is carried out using Markov chain Monte Carlo simulation. By representing the fields in reproducing kernel Hilbert spaces, the degree of overlap can be computed without expensive numerical integration. Superimposing entire fields rather than the configuration matrices of point coordinates thereby avoids the problem that there is usually no clear one-to-one correspondence between the points. In addition, mask parameters are introduced in the model, so that partial matching of the marked point sets can be carried out. We also propose an adaptation of the generalized Procrustes analysis algorithm for the simultaneous alignment of multiple point sets. The methodology is illustrated with a simulation study and then applied to a data set of 31 steroid molecules, where the relationship between shape and binding activity to the corticosteroid binding globulin receptor is explored.Comment: Published in at http://dx.doi.org/10.1214/11-AOAS486 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

Letter from J. Dryden

Letter concerning the cost of a building being built for poultry

Correspondence from Professor Dryden

Correspondence concerning a poultry house being built

The Transition from Welfare to Work

We consider the effects the child care market, child care vouchers, early childhood education programs, and welfare reforms have on welfare recipients in their transition from welfare to work. Specifically, we are interested in determining which factors encourage single mothers to move directly from welfare to work and which factors encourage the pursuit of additional schooling or job retraining before entering the labor market. Using Massachusetts data from July 1996 through August 1997, we find that the availability, quality, and cost of formal child care are all positively related to transiting directly from welfare to work. We also find that single mothers with older children are more likely to pursue a job and forego additional schooling, while single mothers with infants are more likely to advance their education before seeking employment.Welfare Reform, Child Care, Vouchers, Time Limits, Labor Supply

The Transition from Welfare to Work

We consider the effects the child care market, early care and education programs, and welfare reforms have on welfare recipients’ transition from welfare to work. Using 1996-1997 data for Massachusetts, we find that the availability and quality of formal child care, the presence of Head Start and Pre-K programs, and the probability of receiving a child care voucher are all positively related to transiting directly from welfare to work. Single mothers subject to work requirements are more likely to transit directly from assistance to work as well, while those not subject to work requirements are more likely to obtain additional education or job training.

A Structural Equation Model for Tax Compliance and Auditing

In this paper. we estimate a three equation model for taxpayers' reported income and tax liability and for the probability of an audit. Our work differs from previous studies in that our dependent variables in the compliance equations are taxpayer reports rather than a variable related to auditor estimates of noncompliance and in that we estimate a structural equation for audits. We find that audits stimulate compliance although the effect is not large and is not statistically significant for all groups. Audits are more effective at inducing accurate reporting of subtractions from income than of income. Reduced-form results suggest that IRS activities other than audits have significant compliance effects. Results for the sociodemographic variables are interesting and help to explain some seemingly incongruous findings in the literature. We find compliance to be higher, if anything. in areas with less educated and older taxpayers, a large proportion of households headed by females. and a mostly native born population.

Tax Compliance: An Investigation Using Individual TCMP Data

In this paper, we analyze the tax compliance behavior of US taxpayers by using a 1979 data set that combines information from a random sample of individual tax returns each of which has been thoroughly audited, IRS administrative records, and sociodemographic data from the Census. We find evidence that both audits and tax code provisions affect compliance. However, the effects are significant for only the low and high income groups. Interestingly, previous research has shown that these groups also participate most actively in underground economic activities, the income from which is not reported on any tax returns. Our results for audits suggest that the "ripple" or general deterrent effect of audits may be many times larger than the direct revenue yield of audits for high income taxpayers. Our results for allowable subtractions from income imply that the 1986 Tax Reform Act changes to lower allowable subtractions may have procompliance effects.

Child Care and the Welfare to Work Transition

We assess the role of child care in the welfare to work transition using an unusually large and comprehensive data base. Our data are for Massachusetts, a state that began welfare reform in 1995 under a federal waiver, for the period July 1996 through August 1997. We find that both the nature of the child care market and the availability of subsidized care and early education affect the probability that current and former welfare recipients will work. Regarding the child care market, we find that the cost, stability and quality of care matter. We also find that child care subsidies and some types of early education serve to increase employment. To be more specific, we find that increased funding for child care subsidies and the availability of full day kindergarten significantly increase the probability the current and former welfare recipients work.