Browsing Research Articles (Statistics & Population Studies) by Title
Now showing items 99-118 of 165
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Multiple imputation of unordered categorical missing data: A comparison of the multivariate normal imputation and multiple imputation by chained equations
(Brazilian Statistical Association, 2016). Missing data are common in survey data sets. Enrolled subjects do not often have data recorded for all variables of interest. The inappropriate handling of them may negatively affect the inferences drawn. Therefore, special ... -
Multiple regression of GRB luminosity on light-curve properties
(Oxford University Press, 2009)Statistical relations between the luminosity L of gamma-ray burster (GRBs) and several of their other observable properties have been discovered. Four of these properties are considered here: the spectral lag; a measure ... -
Multivariate comparisons of the period–light-curve shape distributions of Cepheids in five galaxies
(Oxford University Press, 2007)A number of published tests suitable for the comparison of multivariate distributions are described. The results of a small power study, based on realistic Cepheid log period – Fourier coefficient data, are presented. ... -
Near-infrared time-series photometry of six fields in the young open cluster IC 2391
(Oxford University Press, 2006)Fields containing targets of spectral types later than M5 were monitored in JHKs for about 7 h each. None of the targets showed variability at levels exceeding 0.02 (or smaller, in some cases). Seven new variable stars ... -
The Nyquist frequency for irregularly spaced time-series: a calculation formula
(Oxford University Press, 2006)Eyer & Bartholdi showed that the Nyquist frequency of irregularly sampled time-series can be very high. In this paper, a calculation formula for the Nyquist frequency is presented. In practice there is an upper limit of ... -
The Nyquist frequency for time series with slight deviations from regular spacing
(Oxford University Press, 2009)The paper is based on the notion that the Nyquist frequency νN is a symmetry point of the periodogram of a time series: the power spectrum at frequencies above νN is a mirror image of that below νN. Koen showed that the ... -
On multiple classes of gamma-ray bursts, as deduced from autocorrelation functions or bivariate duration/hardness ratio distributions
(Oxford University Press, 2012)Autocorrelation functions (ACFs) of 119 gamma-ray bursts (GRBs) monitored by the Burst Alert Telescope (BAT) on Swift are calculated. Contrasting with previous results for smaller numbers of bursts from other missions, ... -
On multiple classes of gamma-ray bursts, as deduced from autocorrelation functions or bivariate duration/hardness ratio distributions
(Oxford University Press, 2012)Autocorrelation functions (ACFs) of 119 gamma-ray bursts (GRBs) monitored by the Burst Alert Telescope (BAT) on Swift are calculated. Contrasting with previous results for smaller numbers of bursts from other missions, ... -
On the nature of the variable star UNSW-V-760
(Oxford University Press, 2011)The results of multicolour photometric monitoring over several nights of the probable X-ray source UNSW-V-760 are presented. Drawing on both present and past observations, it is shown that the star is multiperiodic and ... -
On the upper limit on stellar masses in the Large Magellanic Cloud cluster R136
(Oxford University Press, 2006)A truncated power-law distribution is fitted to the 29 largest stellar masses known in R136. Two different statistical techniques are used, with comparable results. An upper limit to the mass distribution of the order ... -
Overweight/obesity and chronic health conditions in older people with intellectual disability in Ireland
(Wiley, 2021)This study examines overweight/obesity and chronic health conditions (CHCs) in older people with intellectual disability (ID).Data for this cross-sectional observational study emanated from Wave 2 of the Intellectual Disability ... -
An O−C (and light travel time) method suitable for application to large photometric databases
(Oxford University Press, 2014)The standard method of studying period changes in variable stars is to study the timing residuals or O−C values of light-curve maxima or minima. The advent of photometric surveys for variability, covering large parts of ... -
A Panel of Ancestry Informative Markers for the Complex Five-Way Admixed South African Coloured Population
(PloS, 2013)Admixture is a well known confounder in genetic association studies. If genome-wide data is not available, as would be the case for candidate gene studies, ancestry informative markers (AIMs) are required in order to adjust ... -
Patient-Control Association Study of the Leucine-Rich Repeat Kinase 2 (LRRK2) Gene in South African Parkinson's Disease Patients
(National Institute of Health, 2013)The leucine-rich repeat kinase 2 (LRRK2) gene is of interest to Parkinson's disease (PD) as it has been implicated in both familial and sporadic forms of the disorder.1 PD-susceptibility alleles in LRRK2 appear to be ... -
Perinatal suicidality: Risk factors in South African women with mental illness
(OpenJournals Publishing AOSIS (Pty) Ltd, 2020)Maternal Mortality is a global health concern. The lack of suicide data, particularly in low and middle income countries, is concerning and needs to be addressed. Aim: This study assessed suicidality and associated factors ... -
PG 0907+123 and JL 194: slowly pulsating hot subdwarf stars
(Oxford University Press, 2010)Multicolour time-series photometry of two newly discovered slowly pulsating sdB stars (V1093 Her stars, also known as PG 1716 stars) is described. Both stars are fairly bright and appear, from the limited amount of data, ... -
Photometry of the magnetic white dwarf SDSS 121209.31+013627.7
(Oxford University Press, 2006)The results of 27 h of time series photometry of SDSS 121209.31+013627.7 are presented. The binary period established from spectroscopy is confirmed and refined to 0.061 412 d (88.43 min). The photometric variations are ... -
Planned, ongoing and completed tuberculosis treatment trials in Brazil, Russia, India, China and South Africa: A 2019 cross-sectional descriptive analysis
(BMJ Publishing Group, 2022)Tuberculosis (TB) remains a deadly challenge globally and Brazil, Russia, India, China and South Africa (BRICS) are among the countries with the highest TB burden. The objective of this study is to identify and ... -
Pre-race screening and stratification predicts adverse events—A 4-year study in 29585 ultra-marathon entrants, SAFER X
(Wiley-Blackwell, 2020)Pre-race screening and risk stratification in recreational endurance runners may predict adverse events (AEs) during a race. Aim: To determine if pre-race screening and risk stratification predict AEs during a race. Methods: ... -
Pre-race self-reported medical conditions and allergies in 133 641 Comrades ultramarathon (90km) runners - SAFER XXIII
(The Physician and Sportsmedicine, 2023)Objectives: To determine the prevalence of self-reported pre-race chronic medical conditions and allergies in ultramarathon race entrants and to explore if these are associated with an Increased risk of race-day medical ...