A composite estimator for stratified two stage cluster sampling
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- Communications for Statistical Applications and Methods
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- v.23 no.1
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- pp.47-55
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- 2016
Stratified cluster sampling has been widely used for effective parameter estimations due to reductions in time and cost. The probability proportional to size (PPS) sampling method is used when the number of cluster element are significantly different. However, simple random sampling (SRS) is commonly used for simplicity if the number of cluster elements are almost the same. Also it is known that the ratio estimator produces a good performance when the total number of population elements is known. However, the two stage cluster estimator should be used if the total number of elements in population is neither known nor accurate. In this study we suggest a composite estimator by combining the ratio estimator and the two stage cluster estimator to obtain a better estimate under a certain population circumstance. Simulation studies are conducted to compare the superiority of the suggested estimator with two other estimators.
Thecodiplosis japonesis is sweeping the Pinus densiflora forests from south-west to north-east direction, destroying almost all the aged large trees as well as even the young ones. The front line of infestation is moving slowly but ceaselessly norhwards as a long bottle front. Estimation is that more than 40 percent of the area of P. densiflora forest has been damaged already, however some individuals could escapes from the damage and contribute to restore the site to the previous vegetation composition. When the stands were attacked by this insect, the drastic openings of the upper story of tree canopy formed by exclusively P. densiflora are usually resulted and some environmental factors such as light, temperature, litter accumulation, soil moisture and offers were naturally modified. With these changes after insect invasion, as the time passes, phytosociologic changes of the vegetation are gradually proceeding. If we select the forest according to four categories concerning the history of the insect outbreak, namely, non-attacked (healthy forest), recently damaged (the outbreak occured about 1-2 years ago), severely damaged (occured 5-6 years ago), damage prolonged (occured 10 years ago) and restored (occured about 20 years ago), any directional changes of vegetation composition could be traced these in line with four progressive stages. To elucidate these changes, three survey districts; (1) "Gongju" where the damage was severe and it was outbroken in 1977, (2) "Buyeo" where damage prolonged and (3) "Gochang" as restored, were set, (See Tab. 1). All these were located in the south temperate forest zone which was delimited mainly due to the temporature factor and generally accepted without any opposition at present. In view of temperature, the amount and distribution of precipitation and various soil factor, the overall homogeneity of environmental conditions between survey districts might be accepted. However this did not mean that small changes of edaphic and topographic conditions and microclimates can induce any alteration of vegetation patterns. Again four survey plots were set in each district and inter plot distance was 3 to 4 km. And again four subplots were set within a survey plot. The size of a subplot was
Because of accelerated urbanization public body visiting nursing project that started according as matter of health on urban class in the lower brackets of income was concentrated on Social interests has a unsatisfied points to propel project efficiently from the lack of rating materials. Therefore centering around written contents in documentary literature of citizen health by household in five years from starting year of project to now. visiting frequency by medical manpower was evaluated quantitatively and qualitatively in aspect of management hereupon. for the sake of giving a basic materials for public health project of this field. This research presents documentary literature of citizen health which become materials is that as one person's charged region of nurse in duty scale. district is Kang-Buck Gu. the object is resident in the lower brackets of income grounded livelihood protection law and who is admitted by the head of organ~chief of health care). and the number of material centering around the head of a household is 415 copy. The result of research is summarized. as follow. 1. Average visiting frequency examinated by medical manpower show difference according to valuables of supervision characteristics namely average visiting. Frequency of nurse has long term residence in case registration season is early and supervision season is the first year and is high incase a kind of house is unlicdnsed mountain town. Average visiting frequency with doctor is high incase supervision season is the first year and the medical insurance system is admitted by chief of health care. That shows that a man of discomfort behavior left alone are yet many in local society. The meaning of this result shows that the continuity of official relation about class in the lowest brackets of income of long term residence goes well between househole who is a user of visiting nursing service of the object according to midway income under management influences a given duty of nurse s and so causes quantitative decrease. 2. In case behavier and condition of health that nurse diagnoses are bad. as the type matter is a lack of health and the number of patient is large. the average visiting frequency of nurse is high. because average visiting frequency with doctor is high as the condition of health is bad and the number of patient is large. That is similar with that of nurse. CD Average visiting frequency of nurse s seen by matter of disease is very high only in apoplexy by 39.50 and is confined within limits from 7.63 to 11.36 in other disease. But average visiting frequency with doctor is double as many as that of nurse but defined in apoplexy hypertension and articulate. (1) Average visiting frequency of nurse by existence in inoculation of hepatitis is low by 6.73 in unidentified group and very high by 26.89 in group of non-inoculation and the case of the antigenic positive man of B type hepatitis or epileptic who can't be inoculated shows 13.00 and that even family nursing service is needed to them. That result shows that though one person nurse of local charge has a large scale of duty. as visting nursing service is given a class who has a large demand preferentially by respectively accurate nursing diagnosis. the number of diagnosis service is similar with it. 3. During five years. average visiting frequency of nurse is 10.84 and average visiting frequency with doctor is 76.50 seeing from the official scale of nurse. visiting by household is performed two more per year to the average. Seeing this by type of service. average visiting frequency of nurse is higher in indirectly nursing than in directly nursing and that suggests that at the time of visiting household nurse performs education of protection lively save patient but at the time of contrastedly visiting with doctor. directly nursing is more contents of service show no difference by man power and medication dressing by demand is 14.3 and 18.6 the aid of hardship term of doctor and nurse is high by 18.7 and 17.00 in the request of hospitalization when seeing by demands. 4. Action by turns exemplified 1994 is well in sequence of 2/4 turn. 3/4 turn. 1/4 turn. 4/4 turn. When seen by average visiting frequency of nurse but gradually is even. Without difference by turns. average visiting frequency of doctor is much higher in 1/4 turn than other turns. Type of service by turns is all even but directly nursing is inactive in 4/4 and indirectly nursing. Very increases in 4/4 and so. Nurse's quantity of duty is plentiful that shows that by evaluation of last turn and plan of project. Contents of service follows that medication and dressing is the highest by' 5.57 in 1/4turn. goes down gradually by turn. becomes 3.57 in 3/4 turn. and increases again by 4.83 in 4/4 turn. the rest service is higher in 2/4 turn than other turns. 5. Total visiting frequency of nurse is explained to total