Systematic Sampling

2000 ◽  
pp. 727-780
Keyword(s):  
Systematic Sampling

scholarly journals Perinatal Asphyxia Among Neonates Admitted Jimma Medical Center, Jimma, Ethiopia

2020 ◽  
Vol 7 ◽  
pp. 2333794X2098130
Author(s):  
Ebissa Bayana Kebede ◽  
Adugna Olani Akuma ◽  
Yonas Biratu Tarfa
Keyword(s):  
Gestational Age ◽  
Medical Center ◽  
Perinatal Asphyxia ◽  
Mode Of Delivery ◽  
Large For Gestational Age ◽  
Systematic Sampling ◽  
P Value ◽  
Health Extension Workers ◽  
Severe Problem ◽  
Prolonged Labor

Background: Perinatal asphyxia is a severe problem which causes serious problem in neonates in developing countries. This study is aimed to determine magnitude of perinatal asphyxia and its associated factors. Methods: A cross-sectional study design was conducted among neonates admitted over a period of 4 years on 740 samples. Systematic sampling method was employed to get required samples from log book. Epi-data 3.1 is used for data entry and the entered data was exported to SPSS Version 23 for analysis. Bivariable and multiple variable logistic regressions analysis were applied to see the association between dependent and independent variables. Finally, P-value <.05 at 95% CI was declared statistically significant. Results: The main significant factor associated to perinatal asphyxia were prolonged labor ( P = .04, AOR = 1.68 95%CI: [1.00, 2.80]), being primipara ( P = .003, AOR = 2.06, 95%CI: [1.28, 3.30]), Small for Gestational Age (SGA) ( P = .001, AOR = 4.35, 95%CI: [1.85, 10.19]), Large for Gestational Age ( P = .001, AOR = 16.75, 95%CI: [3.82, 73.33]) and mode of delivery. Conclusion: The magnitude of perinatal asphyxia was 18%. Prolonged labor, parity, birth size, mode of delivery, and APGAR score at 1st minute were significantly associated with perinatal asphyxia. So, Nurses, Midwives, Medical Doctors, and health extension workers have to engage and contribute to on how to decrease the magnitude of perinatal asphyxia.

scholarly journals Comparison of Variance Estimators for Systematic Environmental Sample Surveys: Considerations for Post-Stratified Estimation

Forests ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 772
Author(s):  
Bryce Frank ◽  
Vicente J. Monleon
Keyword(s):  
Random Sampling ◽  
Simple Random Sampling ◽  
National Forest Inventory ◽  
Point Estimation ◽  
Systematic Sampling ◽  
Sampling Variance ◽  
Variance Estimators ◽  
The Past ◽  
Point Estimators ◽  
Species Specific

The estimation of the sampling variance of point estimators under two-dimensional systematic sampling designs remains a challenge, and several alternative variance estimators have been proposed in the past few decades. In this work, we compared six alternative variance estimators under Horvitz-Thompson (HT) and post-stratification (PS) point estimation regimes. We subsampled a multitude of species-specific forest attributes from a large, spatially balanced national forest inventory to compare the variance estimators. A variance estimator that assumes a simple random sampling design exhibited positive relative bias under both HT and PS point estimation regimes ranging between 1.23 to 1.88 and 1.11 to 1.78 for HT and PS, respectively. Alternative estimators reduced this positive bias with relative biases ranging between 1.01 to 1.66 and 0.90 to 1.64 for HT and PS, respectively. The alternative estimators generally obtained improved efficiencies under both HT and PS, with relative efficiency values ranging between 0.68 to 1.28 and 0.68 to 1.39, respectively. We identified two estimators as promising alternatives that provide clear improvements over the simple random sampling estimator for a wide variety of attributes and under HT and PS estimation regimes.

Log-Linear Models with Dependent Spatial Data

1983 ◽  
Vol 15 (6) ◽  
pp. 801-813 ◽  
Author(s):  
B Fingleton
Keyword(s):  
Spatial Data ◽  
Statistical Models ◽  
Linear Models ◽  
Square Lattice ◽  
Categorical Variables ◽  
Systematic Sampling ◽  
Pairwise Correlations ◽  
Independent Observations ◽  
Intersection Points ◽  
Log Linear

Log-linear models are an appropriate means of determining the magnitude and direction of interactions between categorical variables that in common with other statistical models assume independent observations. Spatial data are often dependent rather than independent and thus the analysis of spatial data by log-linear models may erroneously detect interactions between variables that are spurious and are the consequence of pairwise correlations between observations. A procedure is described in this paper to accommodate these effects that requires only very minimal assumptions about the nature of the autocorrelation process given systematic sampling at intersection points on a square lattice.

Query Size Estimation for Joins Using Systematic Sampling

2004 ◽  
Vol 15 (3) ◽  
pp. 237-275 ◽  
Author(s):  
A.H.H. Ngu ◽  
B. Harangsri ◽  
J. Shepherd
Keyword(s):  
Systematic Sampling ◽  
Size Estimation ◽  
Query Size Estimation

scholarly journals Willingness of Greek general population to get a COVID-19 vaccine

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Georgia Kourlaba ◽  
Eleni Kourkouni ◽  
Stefania Maistreli ◽  
Christina-Grammatiki Tsopela ◽  
Nafsika-Maria Molocha ◽  
...  
Keyword(s):  
Public Health ◽  
General Population ◽  
Data Collection ◽  
Sample Size ◽  
Significant Proportion ◽  
Control Measures ◽  
Systematic Sampling ◽  
Computer Assisted ◽  
Public Health Officials ◽  
To Receive

Abstract Background Epidemiological data indicate that a large part of population needs to be vaccinated to achieve herd immunity. Hence, it is of high importance for public health officials to know whether people are going to get vaccinated for COVID-19. The objective of the present study was to examine the willingness of adult residents in Greece to receive a COVID-19 vaccine. Methods A cross-sectional was survey conducted among the adult general population of Greece between April 28, 2020 to May 03, 2020 (last week of lockdown), using a mixed methodology for data collection: Computer Assisted Telephone Interviewing (CATI) and Computer Assisted web Interviewing (CAWI). Using a sample size calculator, the target sample size was found to be around 1000 respondents. To ensure a nationally representative sample of the urban/rural population according to the Greek census 2011, a proportionate stratified by region systematic sampling procedure was used to recruit particpants. Data collection was guided through a structured questionnaire. Regarding willingness to COVID-19 vaccination, participants were asked to answer the following question: “If there was a vaccine available for the novel coronavirus, would you do it?” Results Of 1004 respondents only 57.7% stated that they are going to get vaccinated for COVID-19. Respondents aged > 65 years old, those who either themselves or a member of their household belonged to a vulnerable group, those believing that the COVID-19 virus was not developed in laboratories by humans, those believing that coronavirus is far more contagious and lethal compared to the H1N1 virus, and those believing that next waves are coming were statistically significantly more likely to be willing to get a COVID-19 vaccine. Higher knowledge score regarding symptoms, transmission routes and prevention and control measures against COVID-19 was significantly associated with higher willingness of respondents to get vaccinated. Conclusion A significant proportion of individuals in the general population are unwilling to receive a COVID-19 vaccine, stressing the need for public health officials to take immediate awareness-raising measures.

scholarly journals Integrity, use and care of long-lasting insecticidal nets in Kirinyaga County, Kenya

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Mary Nyangi ◽  
Elizabeth Kigondu ◽  
Beatrice Irungu ◽  
Margaret Nganga ◽  
Anthony Gachanja ◽  
...  
Keyword(s):  
Physical Examination ◽  
Vector Control ◽  
Malaria Vector ◽  
Standard Procedure ◽  
Bed Nets ◽  
Malaria Vector Control ◽  
Systematic Sampling ◽  
Significant Difference ◽  
Household Heads ◽  
Long Lasting Insecticidal Nets

Abstract Background Vector control is an essential component in prevention and control of malaria in malaria endemic areas. Insecticide treated nets is one of the standard tools recommended for malaria vector control. The objective of the study was to determine physical integrity and insecticidal potency of long-lasting insecticidal nets (LLINs) used in control of malaria vector in Kirinyaga County, Kenya. Method The study targeted households in an area which had received LLINs during mass net distribution in 2016 from Ministry of Health. A total of 420 households were sampled using systematic sampling method, where the household heads consented to participate in the study. A semi-structured questionnaire was administered to assess care and use while physical examination was used to determine integrity. Chemical concentration was determined by gas chromatography mass spectroscopy (GC-MS). Data analysis was done using Statistical Package for Social Sciences (SPSS) version 19. Results After 18 months of use, 96.9% (95% CI: 95.2–98.6%) of the distributed nets were still available. Regarding net utilization, 94.1% of household heads reported sleeping under an LLIN the previous night. After physical examination, 49.9% (95% CI: 43–52.8%) of the bed nets had at least one hole. The median number of holes of any size was 2[interquartile range (IQR) 1–4], and most holes were located on the lower part of the nets, [median 3 (IQR 2–5)]. Only 15% of the nets with holes had been repaired. The median concentration for α-cypermethrin was 7.15 mg/m2 (IQR 4.25–15.31) and 0.00 mg/g (IQR 0.00–1.99) for permethrin. Based on pHI, Chi-square test varied significantly with the manufacturer (X (6, N = 389) = 29.14, p = 0.04). There was no significant difference between nets with different number of washes (X2(2) = 4.55, p = 0.103). Conclusion More than three-quarters of the nets supplied had survived and insecticidal potency was adequate in vector control. Standard procedure for field evaluation of surface insecticidal content available to a mosquito after landing on a net to rest is recommended.

scholarly journals Rapid continental spread of a salt-tolerant plant along the European road network

2021 ◽  
Author(s):  
R. Fekete ◽  
Gy. Haszonits ◽  
D. Schmidt ◽  
H. Bak ◽  
O. Vincze ◽  
...  
Keyword(s):  
Road Network ◽  
Systematic Sampling ◽  
Road Maintenance ◽  
Salt Tolerant ◽  
Comprehensive Literature Review ◽  
Wide Range ◽  
Significant Difference ◽  
Number Of Individuals ◽  
Germination Experiment ◽  
Plantago Coronopus

AbstractThe spread of alien species with the expansion of road networks and increasing traffic is a well-known phenomenon globally. Besides their corridor effects, road maintenance practices, such as the use of de-icing salts during winter facilitate the spread of halophyte (salt tolerant) species along roads. A good example is Plantago coronopus, a mainly coastal halophyte which has started spreading inland from the Atlantic and Mediterranean coastal habitats, recently reaching even Central European countries (e.g. Hungary). Here we studied the spread of this halophyte and tried to identify factors explaining its successful dispersion along roads, while also comparing native and non-native roadside occurrences with regard to altitude of the localities, size of roadside populations and frequency of roadside occurrences. We completed a comprehensive literature review and collected more than 200 reports of occurrence from roadsides spanning a total of 38 years. During systematic sampling the frequency of the species along roads was significantly higher in the Mediterranean (native area), than along Hungarian (non-native area) roads, however the average number of individuals at the sampling localities were very similar, and no significant difference could be detected. Using a germination experiment, we demonstrate that although the species is able to germinate even at high salt concentrations, salt is not required for germination. Indeed salt significantly decreases germination probability of the seeds. The successful spread of the species could most likely be explained by its remarkably high seed production, or some special characteristics (e.g. seed dimorphism) and its ability to adapt to a wide range of environmental conditions. Considering the recent and rapid eastward spread of P. coronopus, occurrences in other countries where it has not been reported yet can be predicted in coming years.

A note on design-based versus model-based variance estimation in stereology

2002 ◽  
Vol 34 (03) ◽  
pp. 484-490 ◽  
Author(s):  
Asger Hobolth ◽  
Eva B. Vedel Jensen
Keyword(s):  
Mathematical Model ◽  
Original Problem ◽  
Variance Estimation ◽  
Point Of View ◽  
Systematic Sampling ◽  
Variance Estimator ◽  
Shape Model ◽  
Model Based ◽  
Versus Model ◽  
Special Case

Recently, systematic sampling on the circle and the sphere has been studied by Gual-Arnau and Cruz-Orive (2000) from a design-based point of view. In this note, it is shown that their mathematical model for the covariogram is, in a model-based statistical setting, a special case of the p-order shape model suggested by Hobolth, Pedersen and Jensen (2000) and Hobolth, Kent and Dryden (2002) for planar objects without landmarks. Benefits of this observation include an alternative variance estimator, applicable in the original problem of systematic sampling. In a wider perspective, the paper contributes to the discussion concerning design-based versus model-based stereology.

scholarly journals Detecting common mental disorders in primary care in India: a comparison of five screening questionnaires

2007 ◽  
Vol 38 (2) ◽  
pp. 221-228 ◽  
Author(s):  
V. Patel ◽  
R. Araya ◽  
N. Chowdhary ◽  
M. King ◽  
B. Kirkwood ◽  
...  
Keyword(s):  
Primary Care ◽  
Mental Disorders ◽  
Common Mental Disorders ◽  
General Health Questionnaire ◽  
Diagnostic Interview ◽  
Systematic Sampling ◽  
Health Questionnaire ◽  
Primary Care Settings ◽  
Self Reporting Questionnaire ◽  
Distress Scale

BackgroundScreening of patients for common mental disorders (CMDs) is needed in primary-care management programmes. This study aimed to compare the screening properties of five widely used questionnaires.MethodAdult attenders in five primary-care settings in India were recruited through systematic sampling. Four questionnaires were administered, in pairs, in random order to participants: the General Health Questionnaire (GHQ, 12 items); the Primary Health Questionnaire (PHQ, nine items); the Kessler Psychological Distress Scale (K10, 10 items), and from which we could extract the score of the shorter 6-item K6; and the Self-Reporting Questionnaire (SRQ, 20 items). All participants were interviewed with a structured lay diagnostic interview, the Revised Clinical Interview Schedule (CIS-R).ResultsComplete data were available for 598 participants (participation rate 99.3%). All five questionnaires showed moderate to high discriminating ability; the GHQ and SRQ showed the best results. All five showed moderate to high degrees of correlation with one another, the poorest being between the two shortest questionnaires, K6 and PHQ. All five had relatively good internal consistency. However, the positive predictive value (PPV) of the questionnaires compared with the diagnostic interview ranged from 51% to 77% at the optimal cut-off scores.ConclusionsThere is little difference in the ability of these questionnaires to identify cases accurately, but none showed high PPVs without a considerable compromise on sensitivity. Hence, the choice of an optimum cut-off score that yields the best balance between sensitivity and PPV may need to be tailored to individual settings, with a higher cut-off being recommended in resource-limited primary-care settings.

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