A Procedure For Selecting A Best Multinomial Distribution With Application To Population Income Mobility

A procedure is developed for selecting a subset which is asserted to contain the “best” of several multinomial populations with a pre-assigned probability of correct selection. According to a pre-chosen linear combination of the multinomial cell probabilities, the “best” population is defined to be the one with the highest such linear combination. As an illustration, the proposed procedure is applied to data relating to the economics of happiness and population income mobility

A Nonparametric Test For Homogeneity Of Variances: Application To GPAs Of Students Across Academic Majors

We propose a nonparametric (or distribution-free) procedure for testing the equality of several population variances (or scale parameters). The proposed test is a modification of Bakir’s (1989, Commun. Statist., Simul-Comp., 18, 757-775) analysis of means by ranks (ANOMR) procedure for testing the equality of several population means. A proof is given to establish the distribution-free property of the modified procedure. The proposed procedure is then applied to test whether or not the variability in the grade point averages (GPAs) of students differs across five business academic majors. We collect the GPAs (observations) of a random sample of students from each major under study. The absolute deviations of the observations from the overall median of the combined sample are then calculated and ranked from least to largest. The average ranks and two decision lines are then plotted on a graph paper to detect not only the existence of significant differences among variances, but also to pinpoint which variances are causing those differences

Monitoring The Level Of Students GPA's Over Time

A nonparametric (or distribution-free) statistical quality control chart is used to monitor the cumulative grade point averages (GPAs) of students over time. The chart is designed to detect any statistically significant positive or negative shifts in student GPAs from a desired target level. This nonparametric control chart is based on the signed-ranks of the GPAs of the sampled students. The exact false alarm rate and the in-control average run length of the proposed chart can be computed exactly and are independent of the underlying probability distribution of GPAs. The traditional Shewhart X-bar control chart for monitoring the mean of a process is based on the assumption that data follows a normal distribution. However, student GPAs may differ significantly from the normal distribution. As a result, using a traditional control chart to monitor the GPAs of students may lead to incorrectly specifying the control limits and the average run length and/or the false alarm rate of the chart. A test study was conducted at the College of Business Administration at Alabama State University. The study monitored the median cumulative GPAs of management majors during the period Spring 2005 through Spring 2009. The study revealed that the GPAs of students were stable at a median level of 2.6 over the period of the study

A Simple Tool For Quality Assessment In Education

A quality assessment tool is presented to detect the presence of out-of-control conditions in a school course system. The tool detects whether or not a set of courses offered by a certain discipline constitutes a stable (or in-control) system of courses. A system of courses is said to be stable if the variation in students' performance from course to course is only due to common causes. Students' performance in a course may be measured by their term grades in that course or any other method of evaluation. The proposed quality tool has the advantage of being applicable to numerical grades as well as to ordinal letter grades such as A, B, C, etc. A further advantage is that the proposed tool can be implemented graphically as a quality control chart. A pilot case study of the proposed tool was initiated in Fall 1995 to monitor a system of six of basic 200-level courses in the Department of Business Administration at Alabama State University. The results of this pilot study show that the system was out-of-control for the period Fall 1995 to Fall 1999 and then became in-control in Fall 2001

A novel string representation and kernel function for the comparison of I/O access patterns

Parallel I/O access patterns act as fingerprints of a parallel program. In order to extract meaningful information from these patterns, they have to be represented appropriately. Due to the fact that string objects can be easily compared using Kernel Methods, a conversion to a weighted string representation is proposed in this paper, together with a novel string kernel function called Kast Spectrum Kernel. The similarity matrices, obtained after applying the mentioned kernel over a set of examples from a real application, were analyzed using Kernel Principal Component Analysis (Kernel PCA) and Hierarchical Clustering. The evaluation showed that 2 out of 4 I/O access pattern groups were completely identified, while the other 2 conformed a single cluster due to the intrinsic similarity of their members. The proposed strategy can be promisingly applied to other similarity problems involving tree-like structured data

Trends in scapular fractures- a nationwide 17-year study in Finland

Background: The aim of this study was to examine the trends in the number and incidence of scapular fractures causing hospitalization in the Finnish adult population between 1998 and 2014. Methods: We assessed the number and incidence of scapular fractures resulting in hospital admission and fixation with a plate in Finland in 1998 through 2014 using the Finnish National Hospital Discharge Register as the database. In each year, the study included the entire Finnish adult population. Results: A total of 3843 adult patients with scapular fractures were hospitalized, and the incidence of fracture increased from 4.8 (per 100,000 person-years) in 1998 to 6.6 in 2014. The fracture was operated on with plating in 476 cases (12.4%). The annual number and incidence of scapular fixation with plates did not show constant trend changes during the study period except in the years 2011 through 2013, when there was a sudden increase in the number of these operations. This increase leveled off in 2014. Conclusion: The incidence of hospital-treated scapular fractures increased in Finland in 1998 through 2014. Treatment of scapular fractures with a plate did not show consistent trend changes in Finland during this period.Peer reviewe

MP Twitter engagement and abuse post-first COVID-19 lockdown in the UK : white paper

The UK has had a volatile political environment for some years now, with Brexit and leadership crises marking the past five years. With this work, we wanted to understand more about how the global health emergency, COVID-19, influences the amount, type or topics of abuse that UK politicians receive when engaging with the public. With this work, we wanted to understand more about how the global health emergency, COVID-19, influences the amount, type or topics of abuse that UK politicians receive when engaging with the public. This work covers the period of June to December 2020 and analyses Twitter abuse in replies to UK MPs. This work is a follow-up from our analysis of online abuse during the first four months of the COVID-19 pandemic in the UK. The paper examines overall abuse levels during this new seven month period, analyses reactions to members of different political parties and the UK government, and the relationship between online abuse and topics such as Brexit, government's COVID-19 response and policies, and social issues. In addition, we have also examined the presence of conspiracy theories posted in abusive replies to MPs during the period. We have found that abuse levels toward UK MPs were at an all-time high in December 2020 (5.4% of all reply tweets sent to MPs). This is almost 1% higher that the two months preceding the General Election. In a departure from the trend seen in the first four months of the pandemic, MPs from the Tory party received the highest percentage of abusive replies from July 2020 onward, which stays above 5% starting from September 2020 onward, as the COVID-19 crisis deepened and the Brexit negotiations with the EU started nearing completion

Impact of aortic valve effective height following valve-sparing root replacement on postoperative insufficiency and reoperation

BACKGROUND: This study evaluated the impact of anatomic aortic root parameters during valve-sparing root replacement on the probability of postoperative aortic insufficiency and freedom from aortic valve reoperation. METHODS: From 1995 to 2020, 177 patients underwent valve-sparing root replacement (163 reimplantations, 14 remodeling). Preoperative and postoperative echocardiograms were analyzed to measure annulus and sinus diameters, effective height of leaflet coaptation, and degree of aortic insufficiency. Logistic regression was used to evaluate predictors of 2+ or greater late postoperative aortic insufficiency. Fine-Gray regression determined predictors for aortic valve reintervention. RESULTS: The study population included 122 (69%) men with a mean age of 43 ± 15 years. A total of 119 patients (67%) had an identified connective tissue disorder. The cumulative incidence of aortic valve reoperation was estimated as 7% at 5 years and 12% at 10 years. The probability of 2+ or greater late postoperative aortic insufficiency was inversely related to effective height during valve-sparing root replacement (P = .018). As postoperative effective height fell below 11 mm, the probability of 2+ or greater aortic insufficiency exceeded 10%. On multivariable logistic regression, effective height (odds ratio, 0.53; 0.33-0.86; P = .010), preoperative annulus diameter (odds ratio, 1.44; 1.13-1.82; P = .003), and degree of preoperative aortic insufficiency (odds ratio, 2.57; 1.45-4.52; P = .001) were associated with increased incidence of 2+ or greater late postoperative aortic insufficiency. On multivariable Fine-Gray regression, risk factors for aortic valve reintervention included preoperative annulus diameter (subdistribution hazard ratio, 1.28 [1.03-1.59], P = .027), history of 3+ or greater aortic insufficiency (subdistribution hazard ratio, 4.28; 1.60-11.44; P = .004), and 2+ or greater early postoperative aortic insufficiency (subdistribution hazard ratio, 5.22; 2.29-11.90; P \u3c .001). CONCLUSIONS: Measures to increase effective height during valve-sparing root replacement may decrease the risk of more than mild postoperative aortic insufficiency after repair and the need for aortic valve reoperation

Efficient analysis of phased arrays of microstrip patches using a hybrid generalized forward backward method/green's function technique with a DFT based acceleration algorithm

A hybrid method based on the combination of generalized forward backward method (GFBM) and Green's function for the grounded dielectric slab together with the acceleration of the combination via a discrete Fourier transform (DFT) based algorithm is developed for the efficient and accurate analysis of electromagnetic radiation/scattering from electrically large, irregularly contoured two-dimensional arrays consisting of finite number of probe-fed microstrip patches. In this method, unknown current coefficients corresponding to a single patch are first solved by a conventional Galerkin type hybrid method of moments (MoM)/Green's function technique that uses the grounded dielectric slab's Green's function. Because the current distribution on the microstrip patch can be expanded using an arbitrary number of subsectional basis functions, the patch can have any shape. The solution for the array currents is then found through GFBM, where it sweeps the current computation element by element. The computational complexity of this method, which is originally O(Ntot 2 being the total number of unknowns) for each iteration, is reduced to O(Ntot) using a DFT based acceleration algorithm making use of the fact that array elements are identical and the array is periodic. Numerical results in the form of array current distribution are given for various sized arrays of probe-fed microstrip patches with elliptical and/or circular boundaries, and are compared with the conventional MoM results to illustrate the efficiency and accuracy of the method. © 2008 IEEE