The Effect of Medicaid Expansions for Low-Income Children on Medicaid Participation and Insurance Coverage: Evidence from the SIPP

Increased availability of public health insurance for children has led to two potentially contradictory concerns for public policy: that expanded availability of public insurance may lead families to decline private insurance and that additional public coverage may not reach many uninsured children. We examine these two concerns using data from the 1987-1993 Surveys of Income and Program Participation. Using static models we find that the expansions resulted in increased Medicaid coverage, although the estimates of take-up are smaller than estimates from previous research. We find little evidence of a negative relationship of any significant magnitude between eligibility for Medicaid and private coverage. We also find that children who have been eligible for Medicaid longer are more likely to be enrolled in Medicaid but no more likely to have lost private coverage. Including individual fixed effects reduces the magnitude of the estimated take-up effect, while the fixed effects estimates for the private insurance regression become negative and marginally statistically significant in some specifications. Simple dynamic models of insurance choice show that insurance choice is quite persistent. The estimated long run impact of eligibility in the dynamic models is larger than the estimate from the static models, while the immediate impact of expanded Medicaid eligibility from the dynamic models is smaller than the estimated effect from the static models.

Did Expanding Medicaid Affect Welfare Participation?

Using data from the 1988-1996 Current Population Surveys (CPS), we re-examine the evidence presented in Yelowitz (1995) showing that expansions in Medicaid eligibility for children were associated with increased labor force participation and reduced participation in Aid to Families with Dependent Children (AFDC) among single mothers. We find that Yelowitz's results were the result of two factors. First, he imposed a strong restriction on the parameter estimates that is not predicted by theory and is rejected in the CPS data. Second, he used only one of the two income tests that families must pass to be eligible for AFDC, resulting in higher imputed AFDC breakeven income levels for larger families. Once these problems are addressed, the Medicaid income limits have no significant effect on AFDC participation. The AFDC income limits, however, are significantly related to welfare and labor force participation in both his original sample and the entire 1988-1996 sample.

The Effect of Medicaid Expansions for Low-Income Children on Medicaid Participation and Private Insurance Coverage : Evidence from the SIPP

We examine Medicaid enrollment and private coverage loss following expansions of Medicaid eligibility. We attempt to replicate Cutler and GruberÂ’s (1996) results using the Survey of Income and Program Participation, and find smaller rates of take-up and little evidence of crowding out. We find that some of the difference in results can be attributed to different samples and recall periods in the data sets used. Extending the previous literature, we find that take-up is slightly increased if a childÂ’s siblings are eligible and with time spent eligible. Focusing on children whose eligibility status changes during the sample, we estimate smaller take-up effects. We find little evidence of crowding out in any of our extensions.

The Impact of Public Health Insurance on Labor Market Transitions

An often-cited difficulty with moving low-income families out of welfare and into the labor force is the lack of health insurance in many low-wage jobs. Consequently, many low-income household heads may be reluctant to leave welfare and thereby lose health insurance coverage for their children. The expansions in the Medicaid program to cover low-income children and pregnant women who are not eligible for cash benefits may help alleviate the problem by allowing disadvantaged household heads to accept jobs which do not provide health insurance. We use a discrete time (monthly) hazard rate model and data from several panels of the Survey of Income and Program Participation to assess whether expansion of public health insurance to cover children of working parents contributes to increase transitions out of welfare and into employment and reduce transitions into welfare and out of employment. We model spells in progress and spells that start during the sample separately, which allows us to assess the effect on long-term welfare recipients. We find some evidence that expanded Medicaid eligibility for children leads single mothers to exit welfare more quickly; however the effects are not robust to the inclusion of year effects. In addition, the effect appears to be strongest and most consistent among long-term recipients (as proxied by recipients who begin the sample on welfare). We find less evidence of an effect of expanded Medicaid eligibility on transitions into welfare. A somewhat surprising finding is that higher AFDC income limits also appear to have little effect on the probability of such transitions.

Two-Dimensional Spectroscopy of Extended Molecular Systems: Applications to Energy Transport and Relaxation in an α-Helix

A simulation study of the coupled dynamics of amide I and amide II vibrations in an α-helix dissolved in water shows that two-dimensional (2D) infrared spectroscopy may be used to disentangle the energy transport along the helix through each of these modes from the energy relaxation between them. Time scales for both types of processes are obtained. Using polarization-dependent 2D spectroscopy is an important ingredient in the method we propose. The method may also be applied to other two-band systems, both in the infrared (collective vibrations) and the visible (excitons) parts of the spectrum.

Electroweak phase transition in a nonminimal supersymmetric model

The Higgs potential of the minimal nonminimal supersymmetric standard model (MNMSSM) is investigated within the context of electroweak phase transition. We investigate the allowed parameter space yielding correct electroweak phase transitoin employing a high temperature approximation. We devote to phenomenological consequences for the Higgs sector of the MNMSSM for electron-positron colliders. It is observed that a future $e^+ e^-$ linear collider with $\sqrt{s} = 1000$ GeV will be able to test the model with regard to electroweak baryogenesis.Comment: 28 pages, 5 tables, 12 figure

Theory of Spontaneous Polarization of Endohedral Fullerenes

A pseudo-Jahn-Teller model describing central atom distortions is proposed for endohedral fullerenes of the form A@C$_{60}$ where A is either a rare gas or a metal atom. A critical (dimensionless) coupling $g_c$ is found, below which the symmetric configuration is stable and above which inversion symmetry is broken. Vibronic parameters are given for selected endohedral fullerenes.Comment: 4 pages, REVTEX, 1 Postscript figure. [Phys. Rev. Lett. (in press)