33,448 research outputs found
Modelling Charitable Donations to an Unexpected Natural Disaster: Evidence from the U.S. Panel Study of Income Dynamics
Using household-level data, we explore the relationship between donations to the victims of the 2004 Indian Ocean tsunami disaster and other charitable donations. The empirical evidence suggests that donations specifically for the victims of the tsunami are positively associated with the amount previously donated to other charitable causes, which accords with complementary rather than substitution effects. This relationship exists when we decompose overall charitable donations into different types of philanthropy, with charitable contributions to caring, needy and religious organizations having the largest positive association with donations to the victims of the tsunami. When we explore the impact of donations to the victims of the tsunami on future donations to charity, however, our findings suggest an inverse relationship with the largest inverse association with donations to needy and caring organizations
Modelling primary health care use: a panel zero inflated interval regression approach
We introduce the (panel) zero-inflated interval regression (ZIIR) model, to investigate GP visits using individual-level data from the British Household Panel Survey. The ZIIR is particularly suitable for this application as it jointly estimates the probability of visiting the GP and then, conditional on visiting, the frequency of visits (defined by given numerical intervals in the data). The results show that different socio-economic factors influence the probability of visiting the GP and the frequency of visits
Weight losses with low energy formula diets in obese patients with and without type 2 diabetes: Systematic review and meta-analysis
Aim: To provide a systematic review, of published data, to compare weight losses following very low calorie (<800 kcal per day VLCD) or low-energy liquid-formula (>800 kcal per day LELD) diets, in people with and without type 2 diabetes mellitus (T2DM).
Methods: Systematic electronic searches of Medline (1946–2015) and Embase (1947–2015) to identify published studies using formula total diet replacement diets (VLCD/LELD). Random effects meta-analysis using weighted mean difference (WMD) in body weight between groups (with and without diabetes) as the summary estimate.
Results: Final weight loss, in the five included studies, weighted for study sizes, (n=569, mean BMI=35.5–42.6 kg/m2), was not significantly different between participants with and without T2DM: −1.2 kg; 95% CI: −4.1 to 1.6 kg). Rates of weight loss were also similar in the two groups −0.6 kg per week (T2DM) and 0.5 kg per week (no diabetes), and for VLCD (lt;800 kcal per day) and LELD (>800 kcal per day).
Conclusions: Weight losses with liquid-formula diets are very similar for VLCD and LELD and for obese subjects with or without T2DM. They can potentially achieve new weight loss/ maintenance targets of >15–20% for people with severe and medically complicated obesity
Kernel Ellipsoidal Trimming
Ellipsoid estimation is an issue of primary importance in many practical areas such as control, system identification, visual/audio tracking, experimental design, data mining, robust statistics and novelty/outlier detection. This paper presents a new method of kernel information matrix ellipsoid estimation (KIMEE) that finds an ellipsoid in a kernel defined feature space based on a centered information matrix. Although the method is very general and can be applied to many of the aforementioned problems, the main focus in this paper is the problem of novelty or outlier detection associated with fault detection. A simple iterative algorithm based on Titterington's minimum volume ellipsoid method is proposed for practical implementation. The KIMEE method demonstrates very good performance on a set of real-life and simulated datasets compared with support vector machine methods
Assimilation of MSG land-surface temperature into land-surface model simulations to constrain estimates of surface energy budget in West Africa
In the semi-arid regions of West Africa the surface energy partition is related closely to near surface moisture availability. Such moisture availability exhibits marked heterogeneity at scales of a few kilometres, related to the
passage of storm systems during the previous one or two days. The associated variations in surface fluxes affect planetary boundary layer properties at the mesoscale, which may in turn affect rainfall and the seasonal development of the West African monsoon.
Atmosphere models used to study this land-atmosphere coupling are sensitive to the soil moisture initial condition. There exists no observation network for soil moisture in West Africa, so models rely on data from atmosphere analyses, which are often unable to describe adequately surface variation at the mesoscale. Additionally, retrospective estimates of the seasonal surface energy and water budgets using land-surface models are biased by persistent model errors in soil moisture. Anomalies in near-surface (top few centimetres) soil moisture are anti-correlated with anomalies in land-surface brightness temperature, which is observed by the SEVIRI thermal infra-red sensors onboard the Meteosat Second Generation (MSG) satellites. Here, we present methods developed for assimilating the MSG land-surface temperature product from the Land SAF to constrain estimates of the surface energy and water budgets using the JULES land-surface model. This MSG temperature product has a pixel size of approximately 3 km in this region, and is known to provide information of surface wetness anomalies at the scales of interest. The results will provide, for a large region of West Africa, improved initial conditions for modelling studies and seasonal estimates of the surface energy and water budgets
Modelling charitable donations: A latent class panel approach
We apply a latent class tobit framework to the analysis of charitable donations at the household level where the latent class aspect of the model splits households into two groups, which we subsequently interpret as "low" donators and "high" donators. Then the tobit part of the model explores the determinants of the amount donated by each household conditional on being in that class. We consider both total donations and also separately religious donations. Our findings, which are based on US panel data, suggest that price and labour income elasticities differ substantially across the two classes. The inverse price effect is most pronounced for the "low" donators group for both total and religious donations. The labour income elasticity switches direction of influence upon charitable donations across the two latent classes with a negative influence for the "high" donators group and a positive influence for the "low" donators group, for the case of total donations to charity, a pattern which is reversed in the case of solely religious donations
Work in progress: a novel method of creating an academic content repository
This paper outlines a project aimed at addressing the issue of the scalability of online academic support. This project is being run during the Autumn semester at the University of Southern Queensland (USQ) Toowoomba Australia, in conjunction with the Australian Digital Futures Institute. The study attached to the project will use Design-Based Research to evaluate the effectiveness of a simple, but innovative academic content and metadata creation tool referred to as Academic Assist. Academic Assist has been recently developed at USQ as a plug-in block for the moodle-based Learning Management System employed at USQ for its several hundred online subjects. The pilot project and associated study now extends over nine subjects, including three consecutive subjects in computer engineering; and covers faculties of Engineering, Education, Business, Science and Arts. Some preliminary results are presented here. Complete results of the study including acceptance surveys, expert reviews and usage statistics will be presented at FIE 2009
Testing for a unit root in the presence of a possible break in trend
In this paper we consider the issue of testing a time series for a unit root in the possible presence of a break in a linear deterministic trend at some unknown point in the series. We propose a break fraction estimator which, in the presence of a break in trend, is consistent for the true break fraction at rate Op(T^-1) when there is either a unit root or near-unit root in the stochastic component of the series. In contrast to other estimators available in the literature, when there is no break in trend, our proposed break fraction estimator converges to zero at rate Op(T^-1/2). Used in conjunction with a quasi difference (QD) detrended unit root test that incorporates a trend break regressor in the deterministic component, we show that these rates of convergence ensure that known break fraction null critical values are applicable asymptotically. Unlike available procedures in the literature this holds even if there is no break in trend (the true break fraction is zero), in which case the trend break regressor is dropped from the deterministic component and standard QD detrended unit root test critical values then apply. We also propose a second testing procedure which makes use of a formal pre-test for a trend break in the series, including a trend break regressor only where the pre-test rejects the null of no break. Both procedures ensure that the correctly sized (near-) efficient unit root test that allows (does not allow) for a break in trend is applied in the limit when a trend break does (does not) occur.Unit root test; quasi difference de-trending; trend break; pre-test; asymptotic power
Experiments on Visual Acuity and the Visibility of Markings on the Ground in Long-duration Earth-Orbital Space Flight
Visual acuity and visibility of markings on ground in long duration earth orbital space fligh
Modelling Charitable Donations: A Latent Class Panel Approach
Abstract: We apply a latent class tobit framework to the analysis of charitable donations at the household level where the latent class aspect of the model splits households into two groups, which we subsequently interpret as "low" donators and "high" donators. Then the tobit part of the model explores the determinants of the amount donated by each household conditional on being in that class. We consider both total donations and also separately religious donations. Our findings, which are based on US panel data, suggest that price and labour income elasticities differ substantially across the two classes. The inverse price effect is most pronounced for the "low" donators group for both total and religious donations. The labour income elasticity switches direction of influence upon charitable donations across the two latent classes with a negative influence for the "high" donators group and a positive influence for the "low" donators group, for the case of total donations to charity, a pattern which is reversed in the case of solely religious donations.Charity, Donations, Latent Class, Panel Data, Tobit
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