GLUMIP 2.0: SAS/IML Software for Planning Internal Pilots

Internal pilot designs involve conducting interim power analysis (without interim data analysis) to modify the final sample size. Recently developed techniques have been described to avoid the type~I error rate inflation inherent to unadjusted hypothesis tests, while still providing the advantages of an internal pilot design. We present GLUMIP 2.0, the latest version of our free SAS/IML software for planning internal pilot studies in the general linear univariate model (GLUM) framework. The new analytic forms incorporated into the updated software solve many problems inherent to current internal pilot techniques for linear models with Gaussian errors. Hence, the GLUMIP 2.0 software makes it easy to perform exact power analysis for internal pilots under the GLUM framework with independent Gaussian errors and fixed predictors.

The Persistence of Employee 401(k) Contributions Over a Major Stock Market Cycle: Evidence on the Limited Power of Inertia on Savings Behavior

Many middle-income workers save for retirement through 401(k) plans. This study addresses the concern that low account balances of older workers may indicate that these vehicles are not sufficient to insure adequate retirement savings. In particular, the study shows that workers are not persistent (continuing once a worker has started) in contributing, and a weak stock market exacerbates the problem.The study suggests that the concept of inertia, which is in vogue in behavioral economics, does not seem to hold for 401(k) saving behavior. Furthermore, the investment strategy of dollar cost averaging does not seem to hold, either. Using panel data (Panel Study of Income Dynamics) covering a six-year time span from 1999 to 2005, the study presents descriptive and econometric evidence about the persistence behavior of individuals with 401(k) accounts. In particular, the PSID data that were analyzed come from four biannual waves in 1999, 2001, 2003, and 2005. Descriptive data show that of the sample of household heads aged 21-65 in 2005 who were employed in every time period, only about one-third (35 percent) contributed to their plan in all four waves. Job changing had an impact. However, even for individuals in the sample who did not change jobs, less than half (46 percent) contributed in all four years of the survey.An equation modeling 401(k) contribution behavior was estimated using logit regression analysis. When this model was estimated with the sample of individuals who were employed in each panel and with the sample of individuals who were employed in each panel and never changed jobs, the coefficient on the Dow Jones Industrial Average was positive and significant. Workers contributed to their plans when the market was up. This investment error is called herd investing, where individuals get into the market when it is high and not when it is low.The study concludes that the findings have important implications for the pension system and adequacy of retirement income. Projects of future retirement income readiness that assume that workers persistently contribute over their working lives greatly exaggerate the future levels of pension assets workers will have accumulated

GLUMIP 2.0: SAS/IML Software for Planning Internal Pilots

Internal pilot designs involve conducting interim power analysis (without interim data analysis) to modify the final sample size. Recently developed techniques have been described to avoid the type~I error rate inflation inherent to unadjusted hypothesis tests, while still providing the advantages of an internal pilot design. We present GLUMIP 2.0, the latest version of our free SAS/IML software for planning internal pilot studies in the general linear univariate model (GLUM) framework. The new analytic forms incorporated into the updated software solve many problems inherent to current internal pilot techniques for linear models with Gaussian errors. Hence, the GLUMIP 2.0 software makes it easy to perform exact power analysis for internal pilots under the GLUM framework with independent Gaussian errors and fixed predictors

The Persistence of Employee 401(k) Contributions Over a Major Stock Market Cycle: Evidence on the Limited Power of Inertia on Savings Behavior

Many middle-income workers save for retirement through 401(k) plans. This study addresses the concern that low account balances of older workers may indicate that these vehicles are not sufficient to insure adequate retirement savings. In particular, the study shows that workers are not persistent (continuing once a worker has started) in contributing, and a weak stock market exacerbates the problem.The study suggests that the concept of inertia, which is in vogue in behavioral economics, does not seem to hold for 401(k) saving behavior. Furthermore, the investment strategy of dollar cost averaging does not seem to hold, either. Using panel data (Panel Study of Income Dynamics) covering a six-year time span from 1999 to 2005, the study presents descriptive and econometric evidence about the persistence behavior of individuals with 401(k) accounts. In particular, the PSID data that were analyzed come from four biannual waves in 1999, 2001, 2003, and 2005. Descriptive data show that of the sample of household heads aged 21-65 in 2005 who were employed in every time period, only about one-third (35 percent) contributed to their plan in all four waves. Job changing had an impact. However, even for individuals in the sample who did not change jobs, less than half (46 percent) contributed in all four years of the survey.An equation modeling 401(k) contribution behavior was estimated using logit regression analysis. When this model was estimated with the sample of individuals who were employed in each panel and with the sample of individuals who were employed in each panel and never changed jobs, the coefficient on the Dow Jones Industrial Average was positive and significant. Workers contributed to their plans when the market was up. This investment error is called herd investing, where individuals get into the market when it is high and not when it is low.The study concludes that the findings have important implications for the pension system and adequacy of retirement income. Projects of future retirement income readiness that assume that workers persistently contribute over their working lives greatly exaggerate the future levels of pension assets workers will have accumulated

The mass and density of the dwarf planet (225088) 2007 OR10

The satellite of (225088) 2007 OR10 was discovered on archival Hubble Space Telescope images and along with new observations with the WFC3 camera in late 2017 we have been able to determine the orbit. The orbit's notable eccentricity, e$\approx$0.3, may be a consequence of an intrinsically eccentric orbit and slow tidal evolution, but may also be caused by the Kozai mechanism. Dynamical considerations also suggest that the moon is small, D$_{eff}$ $<$ 100 km. Based on the newly determined system mass of 1.75x10$^{21}$ kg, 2007 OR10 is the fifth most massive dwarf planet after Eris, Pluto, Haumea and Makemake. The newly determined orbit has also been considered as an additional option in our radiometric analysis, provided that the moon orbits in the equatorial plane of the primary. Assuming a spherical shape for the primary this approach provides a size of 1230$\pm$50 km, with a slight dependence on the satellite orbit orientation and primary rotation rate chosen, and a bulk density of 1.75$\pm$0.07 g cm$^{-3}$ for the primary. A previous size estimate that assumed an equator-on configuration (1535$^{+75}_{-225}$ km) would provide a density of 0.92$^{+0.46}_{-0.14}$ g cm$^{-3}$, unexpectedly low for a 1000 km-sized dwarf planet.Comment: Accepted for publication in Icaru

Second to fourth digit ratio (2D:4D) and concentrations of circulating sex hormones in adulthood

<p>Abstract</p> <p>Background</p> <p>The second to fourth digit ratio (2D:4D) is used as a marker of prenatal sex hormone exposure. The objective of this study was to examine whether circulating concentrations of sex hormones and SHBG measured in adulthood was associated with 2D:4D.</p> <p>Methods</p> <p>This analysis was based on a random sample from the Melbourne Collaborative Cohort Study. The sample consisted of of 1036 men and 620 post-menopausal women aged between 39 and 70 at the time of blood draw. Concentrations of circulating sex hormones were measured from plasma collected at baseline (1990-1994), while digit length was measured from hand photocopies taken during a recent follow-up (2003-2009). The outcome measures were circulating concentrations of testosterone, oestradiol, dehydroepiandrosterone sulphate, androstenedione, Sex Hormone Binding Globulin, androstenediol glucoronide for men only and oestrone sulphate for women only. Free testosterone and oestradiol were estimated using standard formulae derived empirically. Predicted geometric mean hormone concentrations (for tertiles of 2D:4D) and conditional correlation coefficients (for continuous 2D:4D) were obtained using mixed effects linear regression models.</p> <p>Results</p> <p>No strong associations were observed between 2D:4D measures and circulating concentrations of hormones for men or women. For males, right 2D:4D was weakly inversely associated with circulating testosterone (predicted geometric mean testosterone was 15.9 and 15.0 nmol/L for the lowest and highest tertiles of male right 2D:4D respectively (<it>P</it>-<it>trend </it>= 0.04). There was a similar weak association between male right 2D:4D and the ratio of testosterone to oestradiol. These associations were not evident in analyses of continuous 2D:4D.</p> <p>Conclusions</p> <p>There were no strong associations between any adult circulating concentration of sex hormone or SHGB and 2D:4D. These results contribute to the growing body of evidence indicating that 2D:4D is unrelated to adult sex hormone concentrations.</p

Ozone Depletion from Nearby Supernovae

Estimates made in the 1970's indicated that a supernova occurring within tens of parsecs of Earth could have significant effects on the ozone layer. Since that time, improved tools for detailed modeling of atmospheric chemistry have been developed to calculate ozone depletion, and advances have been made in theoretical modeling of supernovae and of the resultant gamma-ray spectra. In addition, one now has better knowledge of the occurrence rate of supernovae in the galaxy, and of the spatial distribution of progenitors to core-collapse supernovae. We report here the results of two-dimensional atmospheric model calculations that take as input the spectral energy distribution of a supernova, adopting various distances from Earth and various latitude impact angles. In separate simulations we calculate the ozone depletion due to both gamma-rays and cosmic rays. We find that for the combined ozone depletion roughly to double the ``biologically active'' UV flux received at the surface of the Earth, the supernova must occur at <8 pc. Based on the latest data, the time-averaged galactic rate of core-collapse supernovae occurring within 8 pc is ~1.5/Gyr. In comparing our calculated ozone depletions with those of previous studies, we find them to be significantly less severe than found by Ruderman (1974), and consistent with Whitten et al. (1976). In summary, given the amplitude of the effect, the rate of nearby supernovae, and the ~Gyr time scale for multicellular organisms on Earth, this particular pathway for mass extinctions may be less important than previously thought.Comment: 24 pages, 4 Postscript figures, to appear in The Astrophysical Journal, 2003 March 10, vol. 58

Photonic band structure of highly deformable, self-assembling systems

We calculate the photonic band structure at normal incidence of highly deformable, self-assembling systems - cholesteric elastomers subjected to external stress. Cholesterics display brilliant reflection and lasing owing to gaps in their photonic band structure. The band structure of cholesteric elastomers varies sensitively with strain, showing new gaps opening up and shifting in frequency. A novel prediction of a total band gap is made, and is expected to occur in the vicinity of the previously observed de Vries bandgap, which is only for one polarisation