What is stratified sampling technique?4 answersStratified sampling is a technique used to extract samples from a dataset based on specific criteria. It involves dividing the dataset into distinct groups or strata and then selecting samples from each stratum based on predetermined proportions. This method helps ensure that the samples represent the characteristics of the entire dataset accurately. Stratified sampling can be applied in various fields, such as data analysis, water quality sampling, and generating point sets with uniform distribution in hypercubes. It offers advantages such as improved privacy security, direct sampling based on SQL, and avoidance of resource occupation caused by whole-table scanning. The technique can be implemented using different devices and methods, including stratified sampling devices connected to water taking and collecting devices, stratified sampling systems with helix rollers and sampling tubes, and stratification procedures involving recursive binary partitioning.
What is stratified random sampling?5 answersStratified random sampling is a sampling method that involves dividing a population into distinct subgroups or strata based on certain characteristics. Within each stratum, a random sample is then selected. This approach aims to ensure that the sample represents the diversity within the population and allows for more precise estimation by reducing the variance of the estimator. The selection of stratum boundaries and allocation of data to each stratum are important considerations in stratified random sampling. It has been used in various studies, including evaluating the prevalence of infectious diseases like severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Additionally, stratified random sampling has been applied in approximate query processing and developing differential privacy algorithms for constructing confidence intervals.
What is stratified sampling technique?3 answersStratified sampling is a technique used to extract samples from a dataset based on specific criteria. It involves dividing the dataset into distinct groups or strata and then selecting samples from each stratum based on predetermined proportions. This method helps ensure that the sample accurately represents the characteristics of the entire dataset. The stratified sampling technique has various applications, such as in privacy security of sample data, direct stratified sampling based on SQL, water quality sampling, and generating point sets with uniform distribution in hypercubes. It offers advantages such as improved privacy security, efficient data processing, avoidance of resource occupation, and the ability to achieve precise control in sampling.
What are stratified stochasticity trends?5 answersStratified stochastic trends refer to the presence of multiple common stochastic trends in a set of data. These trends can represent different aspects or dimensions of the data, such as shifts, slopes, or curvatures. The identification and estimation of these trends are important in econometric modeling and analysis. For example, Kumah proposes the common trends approach as an alternative to using Solow residuals as proxies for productivity shocks. Zhang finds that there are three common stochastic trends when analyzing the whole spectrum structure of interest rate series, representing the shift, slope, and curvature of the term structure. Bai studies large-dimension factor models with nonstationary dynamic factors, also known as cross-section common stochastic trends, and examines the estimation of these trends and their loading coefficients.
What are some of the problems with a stratified society?5 answersSocial stratification in a society can lead to various problems. Firstly, it results in unequal distribution of resources, leading to some members benefiting greatly while others suffer. This can create social injustice, conflicts, and social divisions based on class, wealth, and power. Additionally, stratified societies tend to have higher levels of relative deprivation, which is associated with a range of social problems such as poor health outcomes, obesity, mental illness, low trust, and low social capital. Unequal access to resources can also be demographically destabilizing, leading to outward migration and the spread of stratified societies. Overall, the problems with a stratified society include inequality, social injustice, conflicts, poor health outcomes, and social divisions based on class and wealth.
When does stratification is done?5 answersStratification is done in various contexts and for different purposes. In the context of thermal stratification in the upper plenum of lead-cooled fast-reactors, it is done to understand the highly dynamic fluid behaviors and their impact on reactor safety. In liquid metal cooled reactors, stratification is studied to analyze the complexities of weakly stratified thermal fronts and their effects on safety. Another context is the stratification of moduli of reduced curves, where a stratification is constructed based on generalized dual graphs and algebraic properties. In the field of healthcare, risk stratification is used to identify patients with acute pulmonary embolism who are at high risk for mortality and require urgent reperfusion therapies. Lastly, in the prevention of arboviral diseases, stratification is used to identify areas with a recurrent concentration of cases and prioritize preventive actions.