Sampling Strata Research Articles

Examining the compensation for the 2010 flood in the Sajó valley using real estate examples

The intention of this article is to investigate the central damage mitigation of the 2010 flood in point of properties. During the investigationI performed the processing of the revealed data on a country level perspicuity, and in details on the level of sample area. In my study I worked with the available damage summations, the number of the damaged properties and the sources granted by central budget to extenuate those,and the husbandry database comparative analysis of local government of the sample strata. It came clear by the analysis of the results, which regions require more acquisition in the further process of the project.

A cross-sectional study of emergency department boarding practices in the United States.

The median emergency department (ED) boarding time for admitted patients has been a nationally reportable core measure that now also affects ED accreditation and reimbursement. However, no direct national probability samples of ED boarding data have been available to guide this policy until now. The authors studied new National Hospital Ambulatory Medical Care Survey (NHAMCS) survey items to establish baseline values, to generate hypotheses for future research, and to help improve survey quality in the future. This was a cross-sectional, multistage, stratified annual analysis of EDs and ED visits from the National Hospital Ambulatory Medical Care Survey public use files from 2007 to 2010, a total of 139,502 visit records. These data represent the only national measure of ED boarding. The main outcome of interest was boarding duration for individual patient visits. Data analyses accounted for complex sampling design. The national median boarding time was 79 minutes, with an interquartile range of 36 to 145 minutes. The prevalence of boarding for more than 2 hours among admitted patients was 32% (95% confidence interval [CI] = 30% to 35%). Average ED volume, occupancy, acuity, and hospital admission rates increased abruptly from the second to the third quartile of median boarding duration. The half of hospitals with the longest median boarding times accounted for 73% of ED visits and 79% of ED hospitalizations nationally. Thirty-nine percent of EDs (95% CI = 32% to 46%) reported never holding patients for more than 2 hours, but visit-level analysis at these EDs found that 21% of admissions did in fact stay in the ED over 2 hours. Only 19% of EDs (95% CI = 16% to 22%) used a strategy of moving admitted patients to alternative sites in the hospital during crowded times. In this national survey, ED boarding of admitted patients disproportionately affects hospitals with higher ED volumes, which also see sicker patients who wait longer to be seen, but not hospitals with higher proportions of Medicaid or uninsured visits. This finding implies that, unlike other quality measures, there is a negative volume-outcome relationship for timely hospitalization from the ED.

A mysterious giant ichthyosaur from the lowermost Jurassic of Wales

Ichthyosaurs rapidly diversified and colonised a wide range of ecological niches during the Early and Middle Triassic period, but experienced a major decline in diversity near the end of the Triassic. Timing and causes of this demise and the subsequent rapid radiation of the diverse, but less disparate, parvipelvian ichthyosaurs are still unknown, notably because of inadequate sampling in strata of latest Triassic age. Here, we describe an exceptionally large radius from Lower Jurassic deposits at Penarth near Cardiff, south Wales (UK) the morphology of which places it within the giant Triassic shastasaurids. A tentative total body size estimate, based on a regression analysis of various complete ichthyosaur skeletons, yields a value of 12–15 m. The specimen is substantially younger than any previously reported last known occurrences of shastasaurids and implies a Lazarus range in the lowermost Jurassic for this ichthyosaur morphotype.

Underground coal gasification: rates of post processing gas transport

AbstractTwo ex-situ and one in-situ semi-pilot plant UCG experiments in the experimental mine Barbara were performed with hard coal and lignite samples. To evaluate the influence of the UCG process on the textural properties of surrounding strata and coals, samples from various locations of the coal seam and the stratum samples before and after the UCG process were collected. Mercury porosimetry, helium pycnometry, and physical adsorption of nitrogen were used for the determination of textural properties of samples. Permeation gas transport was modelled based on the knowledge of the real structure characteristics of the stratum samples by the Mean Transport-Pore Model (MTPM). Influence of the individual texture and transport parameters on the post processing gas transport through porous strata with respect to the variability of their possible values was also evaluated.

Identifying Variables Influencing Tenant Affordability to Pay Rent in Ipoh City Council Public Housing

Affordability reflects the challenges faced by households in balancing the real cost of housing and non housing expenditures against income limitations placed upon the household. Various methods have been introduced to measure housing affordability among households. This study was undertaken to identify the variables influencing tenant affordability to pay rent. Data was obtained through questionnaire distribution on 350 MBI public housing tenants using the strata sampling technique. This study found that only ethnic group variable significantly influenced the ability to pay rent. The study’s findings proved that different ethnic groups faced different housing costs liabilities attributable to different socioeconomic status.

On Compromise Mixed Allocation in Multivariate Stratified Sampling with Random Parameters

For estimating the population mean Clark and Steel (Stat. 49, 1970–207 2000) worked out the optimum allocation of sample sizes to strata and stages with simple additional constraints to use different type of allocations in different strata. Ahsan et al. (Aligarh J. Statist. 25, 87–97 2005) used the same idea to work out optimum allocation in univariate stratified sampling and called it a ‘Mixed Allocation’. Later on Varshney and Ahsan (J. Indian Soc. Agr. Stat. 65(3), 291–296, 2011) extended this work for multivariate stratified sampling and called it a compromise mixed allocation. This article presents a more realistic approach to the compromise mixed allocation by formulating the problem as a Stochastic Nonlinear Programming Problem in which the stratum-wise measurement costs and the sample stratum standard deviations are independent random variables with known probability distributions. The application of this approach is exhibited through a numerical example with normal distributions of the random parameters. The proposed compromise mixed allocation is compared with some other well known compromise allocations available in multivariate stratified sampling literature. It is found that the author’s proposed compromise mixed allocation is the most efficient allocation among the discussed allocations. A simulation study is also carried out to support the claim made by the authors on the basis of the results of the numerical example.

Aspectos epidemiológicos da Doença de Chagas canina no semiárido paraibano

Com o objetivo de determinar os aspectos epidemiológicos que envolvem a doença de Chagas (DC) canina e identificar os principais fatores de risco da enfermidade no semiárido paraibano, foi conduzido um estudo na zona rural de Patos, onde a área foi dividida em três estratos amostrais (Norte, Sul e Oeste) e, em cada estrato foram amostradas aleatoriamente 294 casas, e dessas todos os cães domiciliados representaram as unidades elementares do estudo. Em cada unidade domiciliar foi aplicado um questionário epidemiológico para se obter informações sobre indicadores que favorecem a disseminação da doença no segmento peridomiciliar. O diagnóstico sorológico para DC em cães foi baseado em três métodos (RIFI, ELISA e HAI), sendo consideradas positivas aquelas amostras que apresentassem pelo menos dois testes reagentes e ausência de reatividade cruzada. Para zona rural do município, a prevalência de cães sororreagentes para T. cruzi por estrato amostral foram: Norte 6,05%, Sul 3,59% e Oeste 2,97%, correspondendo a uma prevalência em sua totalidade de 4,08%. Os fatores de riscos (odds ratio, OR) evidenciados em análise multifatorial foram: tipo de parede (OR=2,59 [1,24-5,4]), presença de armazém (OR=1,89 [1,31-3,0]), presença de galinheiros (OR=8,31 [1,29-61,7]), contato com animais (OR=9,11 [1,12-73,9]), contato com aves (OR=9,7 [1,81-52,83]), triatomíneos capturados (OR=16,58 [3,43-80,23]) e antropismo (OR=4,35 [1,36-14,0]. Diante dos resultados foi possível se obter informações inerentes à situação epidemiológica da Doença de Chagas ressaltando características biogeográficas da zona rural do semiárido paraibano, elevando a espécie canina e os fatores de risco evidenciados, em destaque ao contato com aves e ecótopos artificiais, operacionalizando indicadores a serem assistidos e considerados na cadeia de transmissão da doença na região.

Abundancia estacional, fenología reproductiva y uso de hábitat por parte del Mulato (Melanotis caerulescens) en ambientes ribereños del suroeste de Jalisco.

This study describes the seasonal abundance, reproductive phenology and habitat use of the Blue Mockingbird ( Melanotis caerulescens ), an endemic species of Mexico and valued by its singing. The species was sampled using mist-nets during 2 consecutive years in 3 sites of riparian vegetation in the Ayuquila River, Jalisco. The habitat characterization was carried out through sampling strata of trees, shrub, and herbaceous. We used Generalized Linear Models to analyze the differences in coverage strata between the sites, and to identify the effect of site and month on the abundance of the species. The presence of brood patch and cloaca protuberance describes the breeding season between April and August. Blue Mockingbird’s abundance was positively related to sites with greater shrub cover and the site fidelity analysis (individuals’ presence or absence) showed that at least 3 pairs maintained their territories in the study site. These results suggest that maintaining an adequate density of understory shrub in riparian areas is important to provide food and nesting areas. This study is relevant because is the first data published on this issue for this endemic species.

SAT0331 Comparison of Anatomic Knee Alignment on Physical Examination and Radiographs

BackgroundSeverity of knee malalignment is a risk factor for osteoarthritis (OA) progression. Currently the hip-knee-angle, assessed on a full-limb radiograph, is the gold standard. Direct measurement of the anatomic axis...

The implications of spatially varying catchability on bottom trawl surveys of fish abundance: a proposed solution involving underwater vehicles

Bottom trawl sampling is used to estimate trends in stock abundance for groundfishes worldwide, including Pacific rockfishes (Sebastes spp.). However, trawl sampling efficiency varies spatially and the distribution of groundfish populations may change among easy- and difficult-to-survey areas over time. These concerns have prompted interest in using underwater vehicles (UVs), for which catchability is likely to decrease less in rocky habitats. In this study, we use simulation modeling to evaluate the abundance trends arising from bottom trawl sampling given density-dependent habitat selection and spatially varying catchability. We first demonstrate that relative abundance indices in this case will generally be biased measures of changes in population abundance. We also propose and evaluate a sampling design that combines data from bottom trawl and UV gears. Combined sampling has greater precision than UV sampling, lower bias than bottom trawl sampling, and is robust to moderately violated assumptions regarding sampling strata or spatial catchability. We conclude by recommending future research that could test the assumptions under which combined sampling is a feasible solution to spatially varying catchability.

Objective sampling design in a highly heterogeneous landscape - characterizing environmental determinants of malaria vector distribution in French Guiana, in the Amazonian region

BackgroundSampling design is a key issue when establishing species inventories and characterizing habitats within highly heterogeneous landscapes. Sampling efforts in such environments may be constrained and many field studies only rely on subjective and/or qualitative approaches to design collection strategy. The region of Cacao, in French Guiana, provides an excellent study site to understand the presence and abundance of Anopheles mosquitoes, their species dynamics and the transmission risk of malaria across various environments. We propose an objective methodology to define a stratified sampling design. Following thorough environmental characterization, a factorial analysis of mixed groups allows the data to be reduced and non-collinear principal components to be identified while balancing the influences of the different environmental factors. Such components defined new variables which could then be used in a robust k-means clustering procedure. Then, we identified five clusters that corresponded to our sampling strata and selected sampling sites in each stratum.ResultsWe validated our method by comparing the species overlap of entomological collections from selected sites and the environmental similarities of the same sites. The Morisita index was significantly correlated (Pearson linear correlation) with environmental similarity based on i) the balanced environmental variable groups considered jointly (p = 0.001) and ii) land cover/use (p-value << 0.001). The Jaccard index was significantly correlated with land cover/use-based environmental similarity (p-value = 0.001).ConclusionsThe results validate our sampling approach. Land cover/use maps (based on high spatial resolution satellite images) were shown to be particularly useful when studying the presence, density and diversity of Anopheles mosquitoes at local scales and in very heterogeneous landscapes.

Survey data with sampling weights: Is there a “best" approach?

Whether and when to use sampling weights in analyses of complex survey data has been the subject of substantial debate in the statistical and epidemiologic literature; an excellent summary of the issues is given by Korn and Graubard (1999). The exchange in this journal (Kim, 2012; Kim and Kim, 2012; Lee and Kim, 2012) presents two different opinions on the issue. Here, we outline some of the challenges and controversies, and provide some guidance for future work. Complex surveys may sample certain groups or strata at higher rates than others, in order to ensure sufficient precision for group-specific estimates and for bias reduction. Observations are then assigned weights to account for this over-sampling. Additional weighting may also be applied to account for missing data (unit non-response); observations on subjects without missing data are up-weighted in order to represent comparable subjects with missing observations (Brick and Kalton, 1996). An important distinction between the two kinds of weights is that the sampling weights are usually determined by the design, planned in advance, and considered fixed and known, while the missing-data weights are based on a model of the missingness mechanism, i.e., the process that gives rise to missing data. In a complex survey the weights are designed to ensure that the sample is representative of the whole population when the weights are taken into account. Weighted estimates of population-level parameters (e.g., the mean of a continuous outcome variable) are then unbiased, meaning that if the study were repeated infinitely many times, the average parameter estimate should equal the true population parameter. There is relatively little debate on the need to use weighted analysis for this purpose (Korn and Graubard, 1999); it is essential when the mean outcome differs between sampling groups, or in the complete cases vs. the full data. Weighting may be statistically inefficient when the mean outcome does not differ between sampling groups (meaning that standard errors are large

Assessment of physical environment of primary schools in Mosul city

Background: Physical school environment considered one of the critical points for children growth and development. Schools are large places that present significant opportunities for getting an accident or infection. Objective: To assess the physical environmental health criteria of primary schools in Mosul city. Methods: A descriptive cross sectional study design has been adopted. A sample of 25 schools has been taken using multi-stage stratified stratum sampling technique. A special questionnaire form has been prepared depending on WHO criteria for schools environment. A separate questionnaire form has been filled by the investigator herself for each school. Results: Study results revealed that 52% of the schools are near a main street, 80%of schools are close to sources of pollution specially garbages, 20% of schools have maintained gardens, 72% of schools have inadequate faucets, 92% of schools have inadequate toilets. Whereas only 24% of toilets founds have good sanitary conditions. On the other hand only 20% of classrooms were found to be appropriate, 48% of schools were having inadequate lighting and 28% have inadequate ventilation. Keywords: School environment, primary school, physical.

BRAND SWITCHING ANALYSIS IN HAND & BODY LOTION FOR WOMEN CONSUMERS : A CASE STUDY IN STUDENT OF FACULTY PHARMACY UGM

The causes of brand switching are dissatisfaction, the desire of variety and the influence of promotion. This type of research was associative study to analize link between customer dissatisfaction, need to find variations and the influence of promotion on brand Hand&Body Lotion, that causing the brand Switching Hand&Body Lotion. Location of research conducted at the Faculty of Pharmacy UGM, with sample Strata 1 (S1) student, Pharmacist and Master (S2) as many as 200 people. Determination techniques in non-probability sample used was purposive sampling or sampling based on the criteria, the student of Faculty of Pharmacy who using Hand & Body Lotion for 6 months. Data retrieval method used was a questionnaire. The analytical method used was multiple regression method. The result obtained was Y = -1,551 + 0,182X1 + 0,189X2 + 0,215X3 where Y was the displacement of the brand, X1 was the dissatisfaction of consumers, X2 was the need to find variation and X3 the influence of variations in the promotion. Equation can be interpreted that consumer dissatisfaction , needs to find the variety of products and promotional products significantly influenced the decision on Brand Switching Hand & Body Lotion (p <0.05). Promotion variables had the most impact on brand switching by consumers decision between the other independent variables under study that was equal to 0.215. The desire for a variation variable had a constanta 0,189 and 0,82 for advertisment variable. Keyword : Brand switching, dissatisfaction, variation, promotion

Serovariedades y patrones de susceptibilidad a los antimicrobianos de cepas de Salmonella aisladas de alimentos en Cuba

The serotypes of 178 isolates of Salmonella enterica taken from food in different regions of Cuba between January 2008 and December 2009 were identified, and the antimicrobial susceptibility pattern of 100 selected isolates was determined by strata sampling. A total of 20 Salmonella serotypes were identified, with a predominance of S. Enteritidis (23%), S. Agona (13.5%), and S. London (11.2%). Of all the strains, 75% were resistant or presented intermediate resistance to at least one of the drugs tested, in the following order: tetracycline (70.7%), ampicillin (22.7%), and nalidixic acid (14.7%). Ten different resistance patterns were identified. The most frequent patterns corresponded to strains that were either drug-resistant or had intermediate resistance (89.3%). Three strains (identified as S. Infantis, S. Derby, and S. Enteritidis) were multiresistant, and one of them, S. Enteritidis, was not sensitive to either nalidixic acid or ciprofloxacin. To control salmonellosis, the importance of maximizing integrated health surveillance is emphasized.

Larval fish habitats and hydrography in the Biosphere Reserve of the Upper Gulf of California (June 2008)

The Upper Gulf of California (UGC) is a Biosphere Reserve that despite its extreme environmental conditions (macrotidal inverse estuary) houses a high fish species richness. An intensive sampling of fish larvae and hydrography was carried out during June 2008 in the UGC. From 56 zooplankton sampling stations with a maximum of three sampling strata (each 5 m deep, from 0 to 15 m), a total of 29,505 fish larvae were collected, included in 99 taxa and 32 families. The Bray–Curtis Index defined three main larval fish habitats that varied in composition. (i) The “Mixed” larval habitat was mostly defined in the vertically mixed western sector of the UGC; the coastal pelagic Anchoa spp. presented high abundance in this habitat, associated with demersal species such as Gobulus crescentalis and Scianidae type 1. The lowest diversity and abundance, and the highest salinity, temperature and chlorophyll distinguished this larval habitat. (ii) The “Front” habitat was located mostly on the physical–chemical frontal zone between the UGC and the Northern Gulf; it had the highest specific richness and larval abundance. The dominant species were the coastal pelagics Anchoa spp. and Opisthonema sp. 1; the latter was almost limited to the north by the frontal zone. (iii) The “Shelf” habitat, found over the shelf off the mainland, was the deepest and less salty, and was also dominated by Opisthonema sp. 1, but included epipelagic species such as Scombridae (e.g., Scomber japonicus, Auxis spp., Scomberomerus sierra), probably from the adjacent deeper zone. These larval fish habitats had well-defined limits that coincided with marked environmental gradients, with the lowest larval diversity in the saltiest environment; this suggests that the human-induced shift to hypersaline conditions may have reduced the preferred larval habitat for some species. The habitats most likely change with the seasons, with implications for the management of the reserve.

The spatial distribution of Hymenoptera parasitoids in a forest reserve in Central Amazonia, Manaus, AM, Brazil

Parasitoids are of great importance to forest ecosystems due to their ecological role in the regulation of the population of other insects. The species richness and abundance of parasitoids in the forest canopy and understory, both on the borders and in the interior of a tropical forest reserve in Central Amazonia were investigated. For a 12-month period, specimen collections were made every 15 days from suspended traps placed in the forest canopy and in the understory strata, both on the border and in the interior of forest areas. A total of 12,835 Hymenoptera parasitoids from 23 families were acquired. Braconidae, Diapriidae, Mymaridae, Eulophidae, and Scelionidae were the most represented in the area and strata samples. The results indicate that there were no significant differences in the species richness or abundance of Hymenoptera between the forest borders and the inner forest. The data does show that the presence of Hymenoptera is significantly greater in the understory in both the border and interior areas than in the canopy (vertical stratification). Aphelinidae and Ceraphronidae were significantly associated with the inner forest, while the other seven families with the border of the reserve. The abundance of Hymenoptera parasitoids presented seasonal variations during the year related to the rainy and dry seasons.

A Comparison of Factors Associated with Physical Inactivity Among East Asian College Students

Little is known on the level of physical inactivity and its behavioral and cultural correlates among East Asian college students. The aim of this study is to examine and compare the level and behavioral and cultural correlates of physical inactivity among college students in Taiwan, Hong Kong, South Korea, Singapore, and Malaysia. Data were collected from a representative sample of college students (N = 12,137) in five East Asian economies during the 2008-2009 academic year. The stratified random sampling (stratum: geographic region) was used to select participating institutions. The overall response rate was 77%. The percentage of physically inactive students was 7.2% for Singapore, 8.0% for Malaysia, 13.5% for Taiwan, 16.8% for Hong Kong, and 28.5% for South Korea. When gender, age, and body mass index were controlled, fruit and vegetable consumptions were significant correlates for physical inactivity across all the five economies. In Hong Kong, Korea, and Taiwan, those who engaged in binge drinking at least once during the past 2weeks were less likely to be physically inactive than those who did not. Religion and military experience did not independently predict physical inactivity in any of the five economies. Physical inactivity varies greatly across different economies in East Asia that are usually grouped together and considered a single homogeneous entity by some researchers. However, in terms of correlates of physical inactivity, findings of the current study indicate that the transversal value of physical activity might be transformed into a universal.

Assessment of Topical Bioequivalence Using Dermal Microdialysis and Tape Stripping Methods

To assess the bioequivalence of two commercial topical formulations of oxytetracycline HCl by tape stripping and microdialysis in healthy volunteers. Tape stripping study was conducted on 12 healthy volunteers. After a 30-minute application of the formulations, adhesive tapes were used to sample stratum corneum at 0.25, 0.5, 1, 1.5, 2, 3, 4 hr. Ten of these volunteers were included in the microdialysis study with a period of 4 weeks between the experiments. Microdialysis probes were inserted into the dermis of the forearm. Following the application of the test and reference simultaneously, dialysates were collected in 30-minute sampling intervals up to 4 hr. Pharmacokinetic evaluation by microdialysis yielded that the test could not be said to be bioequivalent to the reference at 90% CI. The intersubject variability of oxytetracycline content in stratum corneum was moderate when it was compared to the dermal levels. The test was found to be bioequivalent to reference according to the dermatopharmacokinetic evaluation by tape stripping. No significant correlations were found between microdialysis and tape stripping methods as regarding the topical bioequivalence of oxytetracycline HCl formulations.

Cost‐effective risk assessment of hand‐arm vibration exposure

PurposeAs a tool to help compliance with relevant health and safety legislation, a cost‐effective method of risk assessing construction workers' exposure to hand‐arm vibration (HAV) is presented that allows larger numbers of workers to be evaluated, either as a stratified sample of a population or as a population where numbers are not prohibitive.Design/methodology/approachThe method, developed and tested in the field with a national UK contractor, employs work study to collect exposure level data of workers undertaking real work and analyse these, to inform HAV management and risk control decisions.FindingsThe method benefits from economies of scale to efficiently risk assess large numbers of workers, without the need for specialist equipment or analysis software. It can be applied to sample strata defined by, for example, equipment used, types of work or classifications of worker.Research limitations/implicationsResults add to the growing body of academic knowledge relating to construction worker HAV exposure and its management.Practical implicationsThe method can easily be moulded to suit any type of construction organisation and help control cost associated with HAV legislation compliance.Social implicationsPotential benefits of controlled HAV exposure include reduced incidence of (HAV induced) medical conditions and concomitant personal financial gains to society.Originality/valueThe method and context are novel. The methodology of work study and sampling in a broader sense are well established.