947 resultados para stratified random sampling


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At many locations in Myanmar, ongoing changes in land use have negative environmental impacts and threaten natural ecosystems at local, regional and national scales. In particular, the watershed area of Inle Lake in eastern Myanmar is strongly affected by the environmental effects of deforestation and soil erosion caused by agricultural intensification and expansion of agricultural land, which are exacerbated by the increasing population pressure and the growing number of tourists. This thesis, therefore, focuses on land use changes in traditional farming systems and their effects on socio-economic and biophysical factors to improve our understanding of sustainable natural resource management of this wetland ecosystem. The main objectives of this research were to: (1) assess the noticeable land transformations in space and time, (2) identify the typical farming systems as well as the divergent livelihood strategies, and finally, (3) estimate soil erosion risk in the different agro-ecological zones surrounding the Inle Lake watershed area. GIS and remote sensing techniques allowed to identify the dynamic land use and land cover changes (LUCC) during the past 40 years based on historical Corona images (1968) and Landsat images (1989, 2000 and 2009). In this study, 12 land cover classes were identified and a supervised classification was used for the Landsat datasets, whereas a visual interpretation approach was conducted for the Corona images. Within the past 40 years, the main landscape transformation processes were deforestation (- 49%), urbanization (+ 203%), agricultural expansion (+ 34%) with a notably increase of floating gardens (+ 390%), land abandonment (+ 167%), and marshlands losses in wetland area (- 83%) and water bodies (- 16%). The main driving forces of LUCC appeared to be high population growth, urbanization and settlements, a lack of sustainable land use and environmental management policies, wide-spread rural poverty, an open market economy and changes in market prices and access. To identify the diverse livelihood strategies in the Inle Lake watershed area and the diversity of income generating activities, household surveys were conducted (total: 301 households) using a stratified random sampling design in three different agro-ecological zones: floating gardens (FG), lowland cultivation (LL) and upland cultivation (UP). A cluster and discriminant analysis revealed that livelihood strategies and socio-economic situations of local communities differed significantly in the different zones. For all three zones, different livelihood strategies were identified which differed mainly in the amount of on-farm and off-farm income, and the level of income diversification. The gross margin for each household from agricultural production in the floating garden, lowland and upland cultivation was US$ 2108, 892 and 619 ha-1 respectively. Among the typical farming systems in these zones, tomato (Lycopersicon esculentum L.) plantation in the floating gardens yielded the highest net benefits, but caused negative environmental impacts given the overuse of inorganic fertilizers and pesticides. The Revised Universal Soil Loss Equation (RUSLE) and spatial analysis within GIS were applied to estimate soil erosion risk in the different agricultural zones and for the main cropping systems of the study region. The results revealed that the average soil losses in year 1989, 2000 and 2009 amounted to 20, 10 and 26 t ha-1, respectively and barren land along the steep slopes had the highest soil erosion risk with 85% of the total soil losses in the study area. Yearly fluctuations were mainly caused by changes in the amount of annual precipitation and the dynamics of LUCC such as deforestation and agriculture extension with inappropriate land use and unsustainable cropping systems. Among the typical cropping systems, upland rainfed rice (Oryza sativa L.) cultivation had the highest rate of soil erosion (20 t ha-1yr-1) followed by sebesten (Cordia dichotoma) and turmeric (Curcuma longa) plantation in the UP zone. This study indicated that the hotspot region of soil erosion risk were upland mountain areas, especially in the western part of the Inle lake. Soil conservation practices are thus urgently needed to control soil erosion and lake sedimentation and to conserve the wetland ecosystem. Most farmers have not yet implemented soil conservation measures to reduce soil erosion impacts such as land degradation, sedimentation and water pollution in Inle Lake, which is partly due to the low economic development and poverty in the region. Key challenges of agriculture in the hilly landscapes can be summarized as follows: fostering the sustainable land use of farming systems for the maintenance of ecosystem services and functions while improving the social and economic well-being of the population, integrated natural resources management policies and increasing the diversification of income opportunities to reduce pressure on forest and natural resources.

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El consumo de sustancias psicoactivas (SPA) representa un problema de salud pública en Colombia y en el mundo. La población que recurre a este tipo de sustancias es cada vez más joven y sus efectos son potencialmente deletéreos y pueden afectar todas las áreas de ajuste de la persona. Aunque así se ha concebido, esta práctica no siempre está asociada con problemas personales ni con altos grados de estrés. Puede haber otras motivaciones asociadas. Objetivos: los objetivos de este artículo están dirigidos a presentar: (a) la frecuencia relativa de consumo de SPA entre los estudiantes universitarios, (b) las SPA más utilizadas por los estudiantes universitarios y sus diferencias según el sexo y la edad, (c) la relación entre el uso de SPA y los contextos de diversión. Materiales y métodos: este fue un estudio descriptivo correlacional, derivado de un proyecto de investigación italiano, con una muestra de 226 estudiantes de cuatro carreras de una universidad privada de Bogotá, seleccionados por muestreo aleatorio estratificado con asignación proporcional, a quienes se les aplicó una encuesta. Resultados: las SPA de mayor utilización son el alcohol, la nicotina y la marihuana, cuya mayor predominancia se presenta en el sexo masculino. Los resultados son congruentes con la tendencia nacional. Conclusión: el consumo de SPA en la población universitaria es alto y algunos contextos recreativos están asociados con esta conducta.

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El presente documento tuvo como objetivo el diagnóstico de las prácticas de alimentación de interés en nutrición y salud pública y la percepción de seguridad alimentaria en los hogares del municipio de Pacho departamento de Cundinamarca, información que permitió hacer análisis descriptivo de las frecuencias de consumo de los grupos alimentarios y la cualificación de seguridad en cuanto al acceso a los alimentos. Lo anterior se desarrolló mediante la adaptación de dos de los cinco formularios estructurados para la encuesta nacional de situación nutricional en Colombia del año 2010 liderado por el ministerio de protección social; las encuestas fueron realizadas a 400 personas jefe de hogar de acuerdo a muestreo aleatorio estratificado. El estudio mostró que hay inseguridad alimentaria total en un 34,7%, lo que incluye una percepción de inseguridad en un 3% del total de las familias encuestadas. Por último el estudio permitió concluir la importancia de fortalecer los programas de gobierno existentes, en aras de permitir el favorecimiento de la seguridad alimentaria y nutricional y el cambio de hábitos de nutrición desde una perspectiva intersectorial donde se incluyan los factores sociales, culturales, económicos y ecológicos de la comunidad orientados a estilos de vida saludables transcendentales en prevenir y disminuir el riesgo de enfermedades crónicas no transmisibles.

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El treball desenvolupat en aquesta tesi consisteix en l'adaptació a la llengua catalana d'un model de mesura de la qualitat en el sector serveis, el model servqual, i la seva contrastació a través d'una aplicació empírica al sector de les entitats financeres de les comarques gironines. El primers capítols del treball constitueixen un bloc introductori al tema principal de la tesi, la mesura de la qualitat en el sector serveis, i indiquen la necessitat i la conveniència d'obtenir una mesura fiable de la qualitat per tal d'aconseguir un avantatge competitiu sostenible tant en el mercat nacional com en el mercat internacional actual. El desenvolupament metodològic de la tesi es realitza en dues vessants diferents, per una banda es procedeix a l'adaptació a la llengua catalana de l'instrument de mesura que es vol contrastar, i per l'altra es descriu, es discuteix i s'aplica la metodologia estadística que permet descobrir variables latents, és a dir, constructes no observables directament, a través de l'estudi de la covariació de les variables observables o indicadors adequats. L'objectiu general que es vol aconseguir és l'avaluació de la qualitat percebuda del servei que ofereixen les entitats financeres de la província de Girona. Els objectius específics que es planteja el treball, a part de la obtenció de l'instrument adaptat a la llengua catalana per a la mesura de la qualitat percebuda en el sector de les entitats financeres, són: a) L'estudi de la validesa i de la fiabilitat de l'instrument, així com l'anàlisi de l'estabilitat de les dimensions inherents al model i que porten a la formació del constructe qualitat percebuda. b) L'anàlisi de la relació entre les percepcions i les expectatives com a manera d'avaluar la qualitat percebuda. c) La discriminació deis constructes qualitat, qualitat percebuda i satisfacció i les possibles relacions existents entre ells. d) L'estudi del poder predictiu del constructe qualitat percebuda sobre el comportament futur dels clients. e) L'impacte que tenen les característiques socioeconòmiqes deis clients, així com la distinció entre tipus d'entitat (caixes i bancs), en l'avaluació de la qualitat percebuda. L'elecció del sector empíric d'aplicació del treball no ha estat gratuïta i obeeix a dos motius principals. En primer lloc, i a diferència d'altres treballs empírics d'aplicació de l''escala servqual, no es vol fer l' estudi sobre una mostra de conveniència o sobre una llista de clients d'una determinada entitat sinó que planteja l'estudi sobre una mostra aleatòria geogràfica presa sobre el total poblacional censat a les comarques gironines. L' altra motiu l'imposa la mateixa metodologia al exigir que el client ha d'haver pogut escollir lliurament l'entitat que avalua i per tant que el seu judici sobre l'entitat no ha estat condicionat a priori. La mostra s'ha seleccionat realitzant mostreig aleatori simple proporcional a la mesura de l'hàbitat prèvia estratificació dels municipis segons tinguin mida censal inferior als 2.000 habitants, entre 2.000 i 10.000 habitants, entre 10.000 i 50.000 habitants i superior als 50.000 habitants. El total de la mostra de la primera fase (500 persones), s'ha administrat mitjançant entrevista personal per enquestadors entrenats prèviament. El nivell de resposta útil consta de 430 qüestionaris. La mostra utilitzada en la segona fase consta de 150 persones, seleccionades aleatòriament entre les que havien donar resposta valida en la primera fase i l'administració es va fer per correu. Les anàlisis exploradores realitzades mostren la poca estabilitat de les dimensions del model encara que l'escala de les percepcions recull un percentatge de variabilitat superior a l'escala servqual i proporciona valors superiors per l'alfa de Cronbach. Les anàlisis confirmatòries efectuades per a contrastar l'existència de les cinc dimensions del model (tangible, fiabilitat, interès, seguretat i empatia), com a variables latents associades als seus corresponents models de mesura. ens permeten rebutjar-les globalment encara que observem ajustos menys dolents per al' escala de les percepcions que per a l'escala servqual. L'anàlisi en profunditat del model ens porta a la conclusió que els aspectes més significatius en l'avaluació de qualitat són els corresponents a aspectes de seguretat, fiabilitat i interès i que els percentatges de variabilitat explicada són superiors en tots els casos per a l' escala de les percepcions que per al' escala servqual. Atès que l' anàlisi de la bateria servqual indica que les percepcions dels clients només superen les seves expectatives en tres dels ítems corresponents a la dimensió tangible, que les valoracions de qualitat i de satisfacció global són molt bones i que la comparació de les puntuacions mitjanes a les expectatives amb puntuacions mitjanes d'importància dels diferents aspectes avaluats indiquen criteris semblants, concloem que l'escala de les percepcions té un poder explicatiu superior i que la interpretació de l'escala servqual s'ha de contextualitzar en el sentit que no es poden interpretar de la mateixa manera els gaps amb mateixa puntuació, sinó que la diferencia entre percepcions i expectatives és més important si la puntuació donada a les expectatives és més alta. Les anàlisis efectuades a través de proves Anova i interpretades a través d'anàlisis de classificació múltiple indiquen que els aspectes socioeconòmics que més incideixen en les valoracions de qualitat són els que fan referència a la mida de l'hàbitat i al nivell d'estudis. Veiem el paral·lelisme en l'explicació de les dues escales, percepcions i servqual, però sempre a favor de l'escala de les percepcions pel que fa a significativitat i a percentatge de variabilitat explicada. El model estructural saturat entre els constructes que mesuren de manera global la qualitat, les percepcions de qualitat i la satisfacció global, ens permet rebutjar la hipòtesis que es tracta de mesures de tres constructes iguals i ens permet establir relacions entre ells. El modelat amb equacions estructurals de dos models equivalents excepte pel que fa a la direccionalitat entre qualitat i satisfacció entre les percepcions, la qualitat, la satisfacció i el comportament futur del client, ens porta a ajustos completament equivalents. De la mateixa manera, el planteig de models equivalents per discernir quin dels dos constructes, qualitat o satisfacció, és el que causa un efecte directe sobre el comportament futur del client ens porta també a ajustos equivalents. Les principals conclusions del treball són que les percepcions de qualitat dels clients de les entitats financeres de les comarques gironines són molt bones i que els aspectes més importants per a la valoració de la qualitat són els que fan referència a seguretat, fiabilitat i interès. Els aspectes que fan referència a les dimensions tangibles i d'empatia són molt poc significatius estadísticament. Destaca el fet que l'escala de les percepcions té un poder predictiu més alt a nivell individual que l'escala servqual analitzada i que l'escala de les expectatives permet relativitzar la importància de les conclusions extretes a través de l'escala de les percepcions. S'ha comprovat la validació de criteri de l'instrument a través de la predicció del comportament futur del client en l'ajust estructural realitzat i la fiabilitat de l'instrument s'ha comprovat a través de la prova test-retest efectuada entre les dues fases del treball empíric sobre la mateixa mostra de persones en dos moments de temps. Qualitat i satisfacció són la mesura de dos constructes diferents entre els que no hem pogut decidir el sentit de causalitat. El poder predictiu del constructe qualitat percebuda sobre el comportament futur dels clients es mesura a través d'un efecte indirecte a través de les variables de qualitat i de satisfacció global i és significatiu. Les variables socioeconòmiques són importants per entendre millor el comportament dels diferents sectors de mercat així com dels dos tipus d'entitat avaluades (bancs i caixes). L' escala servqual és un esquelet vàlid per a la mesura de la qualitat dels serveis però cal un treball qualitatiu previ a la seva implantació en un sector concret per recollir una part més gran de la variabilitat de les respostes i la seva força està en la utilització repetida al llarg del temps per captar canvis tant en les expectatives com en les percepcions de qualitat dels clients.

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This paper estimates the determinants of farmers’ decisions to join a rural producer organisation, the National Smallholder Farmers’ Association of Malawi (NASFAM), in Kasungu District. Data for the study were collected in June and August 2003 using household-level questionnaires and stratified random sampling, where strata were membership status and gender. Probit analysis of 250 farmers shows that off-farm sources of income, distance of the farmer’s household from Kasungu District centre, age of the farmer, tobacco farming, education, household level land holding and gender determined the decision to join NASFAM. These results suggest that farmers should be informed of the potential benefits of participating in rural development efforts, and that rural communication and information infrastructure should be improved so as to reduce the costs of information access and transactions in general, if participation in organisations such as NASFAM is to be enhanced.

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It is a known fact that some employees misuse the organizational computers to do their personal work such as sending emails, surfing the Internet, chatting, playing games. These activities not only waste productive time of employees but also bring a risk factor to the organization. This affects organizations in the software industry very much as almost all of their employees are connected to the Internet throughout them day./ By introducing an Acceptable Use Policy (AUP) for an organization, it is believed that the computer misuse by its employees could be reduced. In many countries Acceptable Use Policies are used and they have been studied with various perspectives. In Sri Lankan context research on these areas are scarce. This research explored the situation in Sri Lanka with respect to AUPs and their effectiveness./ A descriptive study was carried out to identify the large and medium scale software development organizations that had implemented computer usage guidelines for employees. A questionnaire was used to gather information regarding employee’s usual computer usage behavior. Stratified random sampling was employed to draw a representative sample from the population./ Majority of the organizations have not employed a written guideline on acceptable use of work computers. The study results did not provide evidence to conclude that the presence or non presence of an AUP has a significant difference in computer use behaviors of employees. A significant negative correlation was observed between level of awareness about AUP and misuse. Access to the Internet and organizational settings were identified as significant factors that influence employee computer misuse behavior.

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The bubble crab Dotilla fenestrata forms very dense populations on the sand flats of the eastern coast of Inhaca Island, Mozambique, making it an interesting biological model to examine spatial distribution patterns and test the relative efficiency of common sampling methods. Due to its apparent ecological importance within the sandy intertidal community, understanding the factors ruling the dynamics of Dotilla populations is also a key issue. In this study, different techniques of estimating crab density are described, and the trends of spatial distribution of the different population categories are shown. The studied populations are arranged in discrete patches located at the well-drained crests of nearly parallel mega sand ripples. For a given sample size, there was an obvious gain in precision by using a stratified random sampling technique, considering discrete patches as strata, compared to the simple random design. Density average and variance differed considerably among patches since juveniles and ovigerous females were found clumped, with higher densities at the lower and upper shore levels, respectively. Burrow counting was found to be an adequate method for large-scale sampling, although consistently underestimating actual crab density by nearly half. Regression analyses suggested that crabs smaller than 2.9 mm carapace width tend to be undetected in visual burrow counts. A visual survey of sampling plots over several patches of a large Dotilla population showed that crab density varied in an interesting oscillating pattern, apparently following the topography of the sand flat. Patches extending to the lower shore contained higher densities than those mostly covering the higher shore. Within-patch density variability also pointed to the same trend, but the density increment towards the lowest shore level varied greatly among the patches compared.

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Objective. To identify families served by the family health strategy (FHS) storing medicines at home, to evaluate storage conditions, and to investigate medicine use practices.Methods. The study was conducted in a municipality in the state of São Paulo with two FHS units serving 1 867 households. The sample was selected by means of stratified random sampling. Data collection was conducted through semistructured interviews from July to October 2008.Results. One resident was interviewed in each of the 280 households visited. Medicines were found in 255 households (91.1%). of 326 storage locations, 217 (75.8%) were inadequate (easily accessible to children or exposed to moisture, light). of the 2 578 medicines identified, 2 059 medicines (79.9%) in 236 (84.3%) households had safety or identification problems. of the 280 respondents, 179 (63.9%) used medications. of these, 24 were self-medicating, only one with an over-the-counter drug. Only 44 users had the prescription for their medication, and 21 did not follow the prescription in terms of dosage or had interrupted the treatment.Conclusions. Non-adherence to recommended treatment can lead to negative outcomes, such as inefficiency (using dosages lower than prescribed), poisoning (using dosages higher than prescribed), and other adverse reactions.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Estimating total landings of artisanal fisheries in managed areas is essential for the development of programs aimed at the establishment of sustainable production systems. However, few experiences addressed the constraints of assessments targeted at multispecific and small scale fisheries with pulverized landings. Total annual production (fish, lobsters and octopus) at the Marine Extractive Reserve of Corumbau, Bahia, Brazil, in 2006, was estimated through yields recorded by fisherfolks, in the scope of a participatory fisheries monitoring program. Three designs were employed: 1) simple random sampling, 2) stratified random sampling by month and fishing frequency, 3) stratified random sampling by community, fishing frequency and months, resulting in estimates of 349t (95% confidence interval = 305-393), 330t (289-372) and 315t (279-351), respectively. This kind of information can help design strategies for aggregation of value to small scale fisheries production, and also for the dimensioning of the corresponding infrastructure. However, these estimates shall not be used to support fishing effort increase, as there is high uncertainty regarding the state of the stocks, as well as limitations related to the asymmetry in monthly landings per fisherfolk and to the sampling coverage in the different strata.

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This study sought to investigate the prevalence of physical inactivity and related barriers in older Brazilian adults. A cross-sectional, population-based study was conducted, and a stratified random sampling procedure was used. A total of 359 older adults were interviewed. The long version of the International Physical Activity Questionnaire (IPAQ) and the Questionnaire of Barriers to Physical Activity Practice were used to assess physical activity level and barriers, respectively. No statistically significant difference was observed on the prevalence of physical inactivity in either gender or age groups. Regarding barriers, the proportion of 9 out of 22 barriers was statistically significant between men and women. Self-reported physical inactivity/activity in older Brazilian adults continues to be a concern. Uncommonly, older males reported a higher prevalence of physical inactivity compared to their counterparts. Additionally, physical inactivity prevalence continued to increase with the aging process. Yet, personal barriers such as lack of time and poor health were strongly associated with physical inactivity. The results of this study may help health professionals and public policy makers to better address the issues related to a healthy lifestyle among older adults and promote physical activity among Brazilian older adults and in other countries with similar characteristics. © 2012 Sebastião Gobbi et al.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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The present study aims to identify families who have stock and are making use of medications, as well as assess the conditions of storage, security and use of these drugs. The study was conducted in a city of São Paulo, the interviews were conducted in households enrolled in one of ten units of the Estratégia de Saúde da Família (ESF) that the city provides and the sample was defined by means of stratified random sampling (134households, IC 95%). Data collection was conducted through interviews with a semistructured questionnaire during the first half of 2011. We interviewed 118 (88.0%) households, of which 112 (95.0%) had medications that were stored n insecure or inadequate places in 75.4% of households, non-prescription self-medication was a common practice in 46 (47 4%) households, and lack of identification and security of medications stored was observed in 60 (53.6%) households. Most households had stock of medicines, which were done improperly or unsecure, or have specialties with lack of identification and security, which can lead to poisoning or e ineffective therapy. The Pharmaceutical Assistance under SUS lacks social initiatives, with actions directed for medications users, which can be supplied by the presence of the pharmacist in the ESF, essential for the promotion of racional use of medicines, that, through the Pharmaceutical Care, can identify, correct and prevent possible problems related to drugs.

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In this paper the influence of a secondary variable as a function of the correlation with the primary variable for collocated cokriging is examined. For this study five exhaustive data sets were generated in computer, from which samples with 60 and 104 data points were drawn using the stratified random sampling method. These exhaustive data sets were generated departing from a pair of primary and secondary variables showing a good correlation. Then successive sets were generated by adding an amount of white noise in such a way that the correlation gets poorer. Using these samples, it was possible to find out how primary and secondary information is used to estimate an unsampled location according to the correlation level.

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Programa de Doctorado: Actividad Física, Salud y Rendimiento Deportivo