781 resultados para design-based survey sampling
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Background: After a myocardial infarction and discharge from the hospital a recovery process follows for the women. In order to facilitate their recovery, both a preventive and promotive perspective should be taken into consideration. Despite this, today´s healthcare focuses more on prevention and thus research into the promotion of women’s recovery process is needed. Aim: To explore how women’s recovery processes are promoted after a first myocardial infarction Methods: The study had an explorative and descriptive design based on qualitative content analysis. Findings: The women’s recovery process was promoted through using external and internal resources as well as embracing behaviour, social and psychological dimensions. The women embraced these dimensions to a varying extent and this process led to them being able to take in a new perspective on life. Conclusions: The women’s personal recovery is a multidirectional process with a desire to develop and approach a new perspective on life. It is important for cardiac rehabilitation nurses to not only focus on lifestyle changes and social support, but also on working actively with the women’s inner strength in order to promote the personal recovery of the women. Furthermore, it would be interesting to investigate men’s experiences of how their recovery process after a first Myocardial infarction is promoted.
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Aims There is scant information on pelvic floor muscle training (PFMT) adherence barriers and facilitators. A web-based survey was conducted (1) to investigate whether responses from health professionals and the public broadly reflected findings in the literature, (2) if responses differed between the two groups, and (3) to identify new research directions. Methods Health professional and public surveys were posted on the ICS website. PFMT adherence barriers and facilitators were divided into four categories: physical/condition, patient, therapy, and social-economic. Responses were analyzed using descriptive statistics from quantitative data and thematic data analysis for qualitative data. Results Five hundred and fifteen health professionals and 51 public respondents participated. Both cohorts felt “patient-related factors” constituted the most important adherence barrier, but differed in their rankings of short- and long-term barriers. Health professionals rated “patient-related” and the public “therapy-related” factors as the most important adherence facilitator. Both ranked “perception of PFMT benefit” as the most important long-term facilitator. Contrary to published findings, symptom severity was not ranked highly. Neither cohort felt the barriers nor facilitators differed according to PFM condition (urinary/faecal incontinence, pelvic organ prolapse, pelvic pain); however, a large number of health professionals felt differences existed across age, gender, and ethnicity. Half of respondents in both cohorts felt research barriers and facilitators differed from those in clinical practice. Conclusions An emphasis on “patient-related” factors, ahead of “condition-specific” and “therapy-related,” affecting PFMT adherence barriers was evident. Health professionals need to be aware of the importance of long-term patient perception of PFMT benefits and consider enabling strategies.
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Objetivo: Determinar la distribución por percentiles de salto con contramovimiento (CMJ) en una población escolar de Bogotá, Colombia, perteneciente al estudio Fuprecol. Métodos: Estudio transversal realizado entre 2846 niños y 2754 adolescentes, entre 9 a 17 años de edad, pertenecientes a 18 instituciones educativas oficiales de Bogotá, Colombia. Se evaluó el CMJ, de acuerdo, con lo establecido por la batería de condición física, Fuprecol. Se calcularon, los percentiles (P3, P10, P25, P50, P75, P90 y P97), y curvas centiles por el método LMS, según su sexo y edad. Se realizó una comparación entre los valores de la CMJ observados con estándares internacionales. Resultados: La muestra estuvo constituida por 5.600 niños y adolescentes entre 9 y 17 años; el promedio de edad fue 12,6 ± 2,4 años. En el CMJ, los valores altos, los obtuvieron los niños, franja en la que la media osciló entre 25,1 cm a los 9 años, y 38,6 cm a los 17; para las niñas, la media fluctuó entre 23,2 cm a los 9 años, y 28,6 a los 17; en ambos sexos esos valores aumentan proporcional a la edad. Conclusiones: Se registran percentiles del CMJ de acuerdo con la edad y el sexo, que podrán ser usados como referencia en la evaluación del salto vertical desde edades tempranas.
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Introducción Las pacientes con miomas uterinos pueden llegar a sufrir de síntomas urinarios y de disfunción sexual. Es para nosotros importante conocer la frecuencia de estas patologías en pacientes con miomas con indicación de cirugía atendidos en el Hospital Universitario Mayor Méderi y la relación entre estas tres entidades. Metodología Estudio cuasi experimental de antes-después. El estudio se encuentra dividido en dos fases, en esta primera fase a las pacientes se les aplicó los cuestionarios FSFI, IIQ-7 y UDI-6 antes de realizar el procedimiento quirúrgico. En una segunda fase se realizará un nuevo abordaje a los 6 y 12 meses donde se aplicarán los mismos instrumentos. Se utilizó coeficiente de Spearman y Kruskall-Wallis para evaluar la relación. Resultados En esta primera fase se incluyeron 81 participantes, con una mediana de años de 46 (RIQ=42-49) mínimo 33 y máximo 71 años. La mediana de miomas fue de 1 (RIQ1-2) máximo 5 miomas. El resultado total de la FSFI fue de 21(RIQ=18,5-25,5). La mediana de la escala UDI -6 fue de 50,4 (RIQ=0-31,2) y la mediana de IIQ-7 fue de 4,75 (RIQ=0-23,7). Se presentó una correlación negativa débil entre los puntajes de FSFI y los cuestionarios UDI-6 (-0.3604) e IIQ 7 (-0.3530), con una prevalencia de riesgo de disfunción sexual de 61%. Conclusiones En esta primera fase de la investigación se pudo observar una existencia de correlación entre la función sexual y la sintomatología urinaria. La prevalencia de disfunción sexual es mayor que en población de mujeres sin patología de miomas uterino.
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El propósito del presente estudio era generar los valores normativos de salto largo para niños de 9-17.9 años, e investigar las diferencias de sexo y grupo de edad
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In next generation Internet-of-Things, the overhead introduced by grant-based multiple access protocols may engulf the access network as a consequence of the proliferation of connected devices. Grant-free access protocols are therefore gaining an increasing interest to support massive multiple access. In addition to scalability requirements, new demands have emerged for massive multiple access, including latency and reliability. The challenges envisaged for future wireless communication networks, particularly in the context of massive access, include: i) a very large population size of low power devices transmitting short packets; ii) an ever-increasing scalability requirement; iii) a mild fixed maximum latency requirement; iv) a non-trivial requirement on reliability. To this aim, we suggest the joint utilization of grant-free access protocols, massive MIMO at the base station side, framed schemes to let the contention start and end within a frame, and succesive interference cancellation techniques at the base station side. In essence, this approach is encapsulated in the concept of coded random access with massive MIMO processing. These schemes can be explored from various angles, spanning the protocol stack from the physical (PHY) to the medium access control (MAC) layer. In this thesis, we delve into both of these layers, examining topics ranging from symbol-level signal processing to succesive interference cancellation-based scheduling strategies. In parallel with proposing new schemes, our work includes a theoretical analysis aimed at providing valuable system design guidelines. As a main theoretical outcome, we propose a novel joint PHY and MAC layer design based on density evolution on sparse graphs.
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The National Cancer Institute (NCI) method allows the distributions of usual intake of nutrients and foods to be estimated. This method can be used in complex surveys. However, the user must perform additional calculations, such as balanced repeated replication (BRR), in order to obtain standard errors and confidence intervals for the percentiles and mean from the distribution of usual intake. The objective is to highlight adaptations of the NCI method using data from the National Dietary Survey. The application of the NCI method was exemplified analyzing the total energy (kcal) and fruit (g) intake, comparing estimations of mean and standard deviation that were based on the complex design of the Brazilian survey with those assuming simple random sample. Although means point estimates were similar, estimates of standard error using the complex design increased by up to 60% compared to simple random sample. Thus, for valid estimates of food and energy intake for the population, all of the sampling characteristics of the surveys should be taken into account because when these characteristics are neglected, statistical analysis may produce underestimated standard errors that would compromise the results and the conclusions of the survey.
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Identifying the geographic distribution of populations is a basic, yet crucial step in many fundamental and applied ecological projects, as it provides key information on which many subsequent analyses depend. However, this task is often costly and time consuming, especially where rare species are concerned and where most sampling designs generally prove inefficient. At the same time, rare species are those for which distribution data are most needed for their conservation to be effective. To enhance fieldwork sampling, model-based sampling (MBS) uses predictions from species distribution models: when looking for the species in areas of high habitat suitability, chances should be higher to find them. We thoroughly tested the efficiency of MBS by conducting an important survey in the Swiss Alps, assessing the detection rate of three rare and five common plant species. For each species, habitat suitability maps were produced following an ensemble modeling framework combining two spatial resolutions and two modeling techniques. We tested the efficiency of MBS and the accuracy of our models by sampling 240 sites in the field (30 sitesx8 species). Across all species, the MBS approach proved to be effective. In particular, the MBS design strictly led to the discovery of six sites of presence of one rare plant, increasing chances to find this species from 0 to 50%. For common species, MBS doubled the new population discovery rates as compared to random sampling. Habitat suitability maps coming from the combination of four individual modeling methods predicted well the species' distribution and more accurately than the individual models. As a conclusion, using MBS for fieldwork could efficiently help in increasing our knowledge of rare species distribution. More generally, we recommend using habitat suitability models to support conservation plans.
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The North American Breeding Bird Survey (BBS) is the principal source of data to inform researchers about the status of and trend for boreal forest birds. Unfortunately, little BBS coverage is available in the boreal forest, where increasing concern over the status of species breeding there has increased interest in northward expansion of the BBS. However, high disturbance rates in the boreal forest may complicate roadside monitoring. If the roadside sampling frame does not capture variation in disturbance rates because of either road placement or the use of roads for resource extraction, biased trend estimates might result. In this study, we examined roadside bias in the proportional representation of habitat disturbance via spatial data on forest “loss,” forest fires, and anthropogenic disturbance. In each of 455 BBS routes, the area disturbed within multiple buffers away from the road was calculated and compared against the area disturbed in degree blocks and BBS strata. We found a nonlinear relationship between bias and distance from the road, suggesting forest loss and forest fires were underrepresented below 75 and 100 m, respectively. In contrast, anthropogenic disturbance was overrepresented at distances below 500 m and underrepresented thereafter. After accounting for distance from road, BBS routes were reasonably representative of the degree blocks they were within, with only a few strata showing biased representation. In general, anthropogenic disturbance is overrepresented in southern strata, and forest fires are underrepresented in almost all strata. Similar biases exist when comparing the entire road network and the subset sampled by BBS routes against the amount of disturbance within BBS strata; however, the magnitude of biases differed. Based on our results, we recommend that spatial stratification and rotating panel designs be used to spread limited BBS and off-road sampling effort in an unbiased fashion and that new BBS routes be established where sufficient road coverage exists.
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Tree-rings offer one of the few possibilities to empirically quantify and reconstruct forest growth dynamics over years to millennia. Contemporaneously with the growing scientific community employing tree-ring parameters, recent research has suggested that commonly applied sampling designs (i.e. how and which trees are selected for dendrochronological sampling) may introduce considerable biases in quantifications of forest responses to environmental change. To date, a systematic assessment of the consequences of sampling design on dendroecological and-climatological conclusions has not yet been performed. Here, we investigate potential biases by sampling a large population of trees and replicating diverse sampling designs. This is achieved by retroactively subsetting the population and specifically testing for biases emerging for climate reconstruction, growth response to climate variability, long-term growth trends, and quantification of forest productivity. We find that commonly applied sampling designs can impart systematic biases of varying magnitude to any type of tree-ring-based investigations, independent of the total number of samples considered. Quantifications of forest growth and productivity are particularly susceptible to biases, whereas growth responses to short-term climate variability are less affected by the choice of sampling design. The world's most frequently applied sampling design, focusing on dominant trees only, can bias absolute growth rates by up to 459% and trends in excess of 200%. Our findings challenge paradigms, where a subset of samples is typically considered to be representative for the entire population. The only two sampling strategies meeting the requirements for all types of investigations are the (i) sampling of all individuals within a fixed area; and (ii) fully randomized selection of trees. This result advertises the consistent implementation of a widely applicable sampling design to simultaneously reduce uncertainties in tree-ring-based quantifications of forest growth and increase the comparability of datasets beyond individual studies, investigators, laboratories, and geographical boundaries.
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This multicentric population-based study in Brazil is the first national effort to estimate the prevalence of hepatitis B (HBV) and risk factors in the capital cities of the Northeast, Central-West, and Federal Districts (2004-2005). Random multistage cluster sampling was used to select persons 13-69 years of age. Markers for HBV were tested by enzyme-linked immunosorbent assay. The HBV genotypes were determined by sequencing hepatitis B surface antigen (HBsAg). Multivariate analyses and simple catalytic model were performed. Overall, 7,881 persons were included; < 70 per cent were not vaccinated. Positivity for HBsAg was less than 1 per cent among non-vaccinated persons and genotypes A, D, and F co-circulated. The incidence of infection increased with age with similar force of infection in all regions. Males and persons having initiated sexual activity were associated with HBV infection in the two settings; healthcare jobs and prior hospitalization were risk factors in the Federal District. Our survey classified these regions as areas with HBV endemicity and highlighted the risk factors differences among the settings
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Degenerative aortic valve disease (DAVD), a common finding in the elderly, is associated with an increased risk of death due to cardiovascular causes. Taking advantage of its longitudinal design, this study evaluates the prevalence of DAVD and its temporal associations with long-term exposure to cardiovascular risk factors in the general population. We studied 953 subjects (aged 25-74 years) from a random sample of German residents. Risk factors had been determined at a baseline investigation in 1994/95. At a follow-up investigation, 10 years later, standardized echocardiography determined aortic valve morphology and aortic valve area (AVA) as well as left ventricular geometry and function. At the follow-up study, the overall prevalence of DAVD was 28%. In logistic regression models adjusting for traditional cardiovascular risk factors at baseline age (OR 2.0 [1.7-2.3] per 10 years, P < 0.001), active smoking (OR 1.7 [1.1-2.4], P = 0.009) and elevated total cholesterol levels (OR 1.2 [1.1-1.3] per increase of 20 mg/dL, P < 0.001) were significantly related to DAVD at follow-up. Furthermore, age, baseline status of smoking, and total cholesterol level were significant predictors of a smaller AVA at follow-up study. In contrast, hypertension and obesity had no detectable relationship with long-term changes of aortic valve structure. In the general population we observed a high prevalence of DAVD that is associated with long-term exposure to elevated cholesterol levels and active smoking. These findings strengthen the notion that smoking cessation and cholesterol lowering are promising treatment targets for prevention of DAVD.
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Background: The aim of this report is to describe the main characteristics of the design, including response rates, of the Cornella Health Interview Survey Follow-up Study. Methods: The original cohort consisted of 2,500 subjects (1,263 women and 1,237 men) interviewed as part of the 1994 Cornella Health Interview Study. A record linkage to update the address and vital status of the cohort members was carried out using, first a deterministic method, and secondly a probabilistic one, based on each subject's first name and surnames. Subsequently, we attempted to locate the cohort members to conduct the phone follow-up interviews. A pilot study was carried out to test the overall feasibility and to modify some procedures before the field work began. Results: After record linkage, 2,468 (98.7%) subjects were successfully traced. Of these, 91 (3.6%) were deceased, 259 (10.3%) had moved to other towns, and 50 (2.0%) had neither renewed their last municipal census documents nor declared having moved. After using different strategies to track and to retain cohort members, we traced 92% of the CHIS participants. From them, 1,605 subjects answered the follow-up questionnaire. Conclusion: The computerized record linkage maximized the success of the follow-up that was carried out 7 years after the baseline interview. The pilot study was useful to increase the efficiency in tracing and interviewing the respondents.
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Because data on rare species usually are sparse, it is important to have efficient ways to sample additional data. Traditional sampling approaches are of limited value for rare species because a very large proportion of randomly chosen sampling sites are unlikely to shelter the species. For these species, spatial predictions from niche-based distribution models can be used to stratify the sampling and increase sampling efficiency. New data sampled are then used to improve the initial model. Applying this approach repeatedly is an adaptive process that may allow increasing the number of new occurrences found. We illustrate the approach with a case study of a rare and endangered plant species in Switzerland and a simulation experiment. Our field survey confirmed that the method helps in the discovery of new populations of the target species in remote areas where the predicted habitat suitability is high. In our simulations the model-based approach provided a significant improvement (by a factor of 1.8 to 4 times, depending on the measure) over simple random sampling. In terms of cost this approach may save up to 70% of the time spent in the field.