A Bootstrap Test for Informative Intra-Cluster Group Sizes in Clustered Data

Clustered data are frequently observed in various domains of scientific and social studies. In a typical clustered data, units within a cluster are correlated while units between different clusters are independent. An example of such clustered data can be found in dental studies where individuals are treated as clusters and the teeth in an individual are the units within a cluster. While analyzing such clustered data, it has been observed that the number of units present in a cluster can be informative in terms of being associated with the outcome from that cluster. Specifically, when the aim is to compare the outcomes from two different groups of units (e.g., upper teeth vs. lower teeth) in a clustered data, then the number of units belonging to a group in a typical cluster, i.e., an intra-cluster group size, can be informative about the outcome from that group in that cluster. Although such clustered data analysis has recently gained importance, there does not exist any formal statistical method for testing the hypothesis that a particular clustered data has informative intra-cluster group sizes (IICGS). However, ignoring the existence of this IICGS during group-based outcome comparisons in a clustered data can result in a biased inference. In this research, we focus on developing a statistical hypothesis testing mechanism that can test a claim of IICGS in a clustered data setting. We use Kolmogorov-Smirnov test-type nonparametric test statistic and a bootstrap hypothesis testing procedure to develop our testing method. Through a variety of simulated data, we demonstrate that our proposed statistical testing method maintains the nominal type-I error rate and has substantial power in identifying IICGS in a clustered data.https://digitalcommons.odu.edu/gradposters2023_sciences/1006/thumbnail.jp

Predicting the Winning Percentage of Limited-Overs Cricket Using the Pythagorean Formula

The Pythagorean Win-Loss formula can be effectively used to estimate winning percentages for sporting events. This formula was initially developed by baseball statistician Bill James and later was extended by other researchers to sports such as football, basketball, and ice hockey. Although one can calculate actual winning percentages based on the outcomes of played games, that approach does not take into account the margin of victory. The key benefit of the Pythagorean formula is its utilization of actual average runs scored and actual average runs allowed. This article presents the application of the Pythagorean Win-Loss formula to two different types of limited-overs cricket formats, namely One Day International cricket (ODI) and Twenty20 cricket. The data for the application was used from the matches played by the top 10 International Cricket Council (ICC) members who participated in the 2019 ICC Cricket World Cup. For matches for which the second batting team won, runs scored were estimated by considering the remaining amount of resources, based on the Duckworth-Lewis method

Exploring students’ satisfaction in the university learning environment: A study of newly introduced courses for state universities in Sri Lanka

Newly introduced undergraduate courses in state universities failed due to various reasons. The purpose of this study is to explore the factors that affect student satisfaction in the learning environment and to which extent such factors influence the learning behaviour of university students. The study adopts the nudge theory to analyse the students’ decision making based on choice architecture and the constructivist grounded theory, which explores how students determine satisfaction with learning. This study has been conducted in the context of the students who follow newly introduced courses in state universities in Sri Lanka. The study has applied quantitative research design to answer the research questions following the survey method. The conceptual framework of the study focuses on physical and intellectual support factors in the learning environment to measure student satisfaction. The results derive that academic support provided by the staff is the main factor to satisfy the students in the learning environment, which has a significant relationship. Support of the library has been identified as a factor which negatively affects student satisfaction. The study reveals that how students’ decision-making behaviour can be analysed through nudging. The primary contribution of the study is to the literature on identifying key factors which assist students in the learning environment to do the studies satisfactorily when they read for newly introduced courses in state universities. The study develops a novel theoretical structure through nudge theory to identify the students’ behaviour and satisfaction level. The practical implications are vital in this study which indicates that important aspects of developing in higher education in Sri Lanka to improve the quality of newly introduced courses in business. Keywords: Satisfaction, Learning environment, Nudg

Modeling Joint Survival Probabilities of Runs Scored and Balls Faced in Limited Overs Cricket Using Copulas

In limited overs cricket, the goal of a batsman is to score a maximum number of runs within a limited number of balls. Therefore, the number of runs scored and the number of balls faced are the two key statistics used to evaluate the performance of a batsman. In cricket, as the batsmen play as pairs, having longer partnerships is also key to building strong innings. Moreover, having a steady opening partnership is extremely important as a team aims to build such a stronger innings. In this study, we have shown a way to evaluate the performance of opening partnerships in Twenty20 (T20) cricket and the performance of individual batsmen in One Day International Cricket (ODI) by modeling the joint distribution of runs scored and balls faced using copula functions. The joint survival probabilities derived from this approach are then used to evaluate the batting performance of opening partnerships and individual batsmen for different stages of the innings. Results of the study have shown that cricket managers and team officials can use the proposed method in selecting appropriate partnership pairs and individual batsmen in an efficient manner for specific situations in the match

Simulation of Bedrock Motion to Obtain PGA Values

This study is focused on producing the Peak Ground Acceleration (PGA) values for important cities in Sri Lanka, which would provide the base to develop the national annex to the Euro Code, the current guideline in designing structures. In order to find out the magnitude and the epicenter distance of a 475-year return period earthquake, an earthquake catalog was developed. To simulate the bedrock motion FLAC Software, which uses the Finite Difference approach, was used. Five 2-D FLAC models representing five cross sections of Sri Lanka were developed. Due to the lack of local data records, a dataset of seven earthquakes with the magnitude of a 475- year return period was selected from the Pacific Earthquake Engineering Research Center (PEER) database. The model was then analyzed—one cross section for each of the seven earthquakes. The resultant acceleration time histories were converted into a response spectrum, and the average spectrum for each city was obtained

Samples for 3rd Harmonic Magnetometry Assessment of NbTiN-Based SIS Structures

In the quest for alternative superconducting materials to bring accelerator cavity performance beyond the bulk niobium (Nb) intrinsic limits, a promising concept uses superconductor-insulator-superconductor (SIS) thin film structures that allows magnetic flux shielding in accelerator cavities to higher fields [1]. Candidate materials for such structures are NbTiN as the superconductor and AlN as the insulator. We have demonstrated high quality NbTiN and AlN deposited by reactive DC magnetron sputtering (DCMS), both for individual layers and multilayers. Interface quality has been assessed for bilayer stacks with 250 nm NbTiN layers and AlN thicknesses from 30 nm down to1 nm. These SIS structures show continued sharp interfaces with total average roughness under 2 nm. The Hfp enhancement of the films will be examined with a 3rd harmonic magnetometry. The system is being designed and built in a continuing collaboration with CEA Saclay. It can measure 25 to 50 mm samples on a temperature controlled stage. This contribution presents an overview of the design of the 3rd harmonic magnetometer and the material properties assessment of standalone films and multilayer nanostructures

TREND IN USAGE OF CFC'S IN SRI LANKA AND PHASE OUT UNDER MONTREAL PROTOCOL

With the development of halogenated hydrocarbons by E.I.Du Pont deNemours & Co (USA) as refrigerants, there had been an increase in usage ofthese chloroflurocarbons (CFCs) in refrigeration applications worldwidesince 1950, mainly because these substances have excellent thermodynamicand safety characteristics. In Sri Lanka the consumption of CFC wasincreased rapidly up to 1995 (Table 1). Scientists had discovered the effectsof CFCs on the earth's ozone layer in nineteen seventies and it was agreed bylarge number of countries to phase out the production and usage of CFCs bybecoming party to the Montreal Protocol. The Montreal Protocol on OzoneDepleting Substances (ODS) was signed in 1987 to implement the phase outprogramme. Sri Lanka became a party to this Protocol in 1989 and is boundto implement phase out ODSs by dates. specified by the Protocol. In order toreach that target, National Ozone Unit (NOU) was established in the Ministryof Environment and Natural Resources in 1994. NOU has implementedseveral projects in order to reduce consumption of CFC with the assistance ofMultilateral Fund (MLF) of the Protocol.Sri Lanka has introduced a licensing system in 1998 to control the imports ofCFCs and so far achieved successful reduction of CFC consumption. Thetable 1 shows the downward trend of CFC consumption as a result of actiontaken by the NOU. As an Article 5 country under the Montreal Protocol SriLanka need to phase out CFC consumption by 2010. However, Sri Lanka hastaken steps to phase out CFC by the end of 2007.To achieve phase out as planned, three refrigerator manufacturers werefunded to con vert from CFC -11 to HCFC -141 b and from CFC 12 to R 134a,converted an aerosol manufacturing plant from CFC 12 to Hydrocarbons andlaunched a scheme to pay incentives for converting CFC refrigeration plants to non-Cf'Cs. In addition the NOU has taken steps in awareness creation,training of refrigeration technicians and recovery and recycling of CFC. As aresult, consumption of CFC in the manufacturing sector has been phased outand remaining consumption in the servicing sector could be eliminatedthrough projects already planned.Apart from ozone layer depletion, CFCs are powerful greenhouse gases muchstronger than C02. Therefore it is important to reduce emission of CFC notonly to save the ozone layer but also to prevent global warming and climatechange.

A PRELIMINARY INVESTIGATION ON TRADITIONAL TAPPING METHODS OF 'KITUL' OR THE FISH·TAIL PALM (Caryota urens L.)

Rural survival depends largely on the wealth or the natural environment. "Kitul" or theFish-tail palm is one or the important species which has been exploited from the wild hythe villagers from the ancient past. Tapping the inllorescence 01" the Kitul tree forcollecting the phloem sap for producing jaggnry, treacle and toddy has he en generatingpractices, among the rural folk in some villages particularly those abutting the naturalforests. The tapping process makes direct use of the transport mechanism of the tree inwhich the assimilates arc moved to the developing organs. The method of tapping differsfro II I "Lice to place. Usually tappers use plant extracts for seasoning the inflorescenceherol,' r.ipping. The purpose of using these various plant extracts is the arresting of thcmaturation of the inflorescence and the increasing of thc sap Ilow. The knowledge 01" theseindigenous tapping practices arc not being handed down the generations and thereforebeing gradually lost. This paper presents the results of a preliminary investigation thetraditional tapping methods of Kitul by the people in villages abutting the Sinharaja forestand the Knuckcls ranges

Environmental contamination of pathogenic and intermediate pathogenic <em>Leptospira</em> spp in two divisional secretariats of Kandy district

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