Drawing a stratified sample in stata Wellington
Stata FAQ Random samples from an existing dataset Downloadable! This program was written primarily for drawing a sample by the randomly split zones (rsz) for samples of size one sampling method as proposed in Singh and Ye (Proc. ASA, SRM, 2016). It also provides the option to draw a sample by simple random (srs) sampling method or the systematic (sys) sampling method. Under the rsz sampling
How to Create A Stratified Random Sample in Excel YouTube
Disproportionate Stratified Sampling – Healthcare Economist. The Stata command sample codifies one approach to choosing a sample without replacement. The concern here is with explaining enough basic ideas that you can produce your own random samples as desired in Stata with a combination of elementary Stata commands., The Stata command sample codifies one approach to choosing a sample without replacement. The concern here is with explaining enough basic ideas that you can produce your own random samples as desired in Stata with a combination of elementary Stata commands..
1. Sample randomly a percentage of observations from the large dataset (10%) 2. Sample randomly a fixed number of observations from the large dataset (5,000) In our case we know that both should give us about the sample size we want because we know the actual number of observations in the population. Stata code for Sampling . Introduction This is a basic introduction to the code that can be used for doing design effect and sample size calculations in Stata. There are other options – many samplers use SAS, Excel, or Optimal Design to do their calculations. 2 . Design Effects •In order to calculate design effects for a particular dataset, you first need to define the complex design for
Sample Size Estimation for Stratified Sampling Design • Sample size estimation for stratified sampling is difficult in practice, not for the complexity of sample size formula. • Sample size estimation depends on variance estimation. Consider the variance of a mean for a variable y: h h h h h H h h h h h h h H h h h h h h h H h h h str str N For information how to draw a stratified random sample, see Stratified Random Sample. Why Use Stata to Randomize? Randomizing in Stata and subsequently preloading the generated data file into the survey software is the preferred method to randomizing in Excel or randomizing in survey software. The main advantages of randomizing in Stata follow:
In stratified sampling, we usually apply specific (identical or different) sampling fractions to different groups (strata) in the population to draw the sample. In STATISTICA, we can draw stratified random samples by using the Random Sampling options. Over-sampling particular strata … 19/01/2013 · 5-Minute tutorial on how to create a stratified random sample in Excel.
stratified sample) We save the stratified sample in a folder. The name of the data set is stratifiedBMI.dta Fares Qeadan, Ph.D (Department of Internal Medicine Division of Epidemiology, Biostatistics, & Preventive MedicineUniversity of New Mexico Health Sciences Center)Sampling Methods Using STATA September 14, … Stratified Sampling. Question 1. (travel agency) Target population: People aged 20-65 years. We can draw a sample of 1000 persons using Stratified sampling.
onsider a sampling scenario: we need to draw 300 samples. We may draw 10 clusters ters with 100 elements. We have said earlier, the uster sampling is to reduce costs. Obviously, the 2. nd. 3 clusters. However, as we have shown above, eff. As a result, the first option should be ” essons for Cluster Sampling • Use as many clusters as Downloadable! This program was written primarily for drawing a sample by the randomly split zones (rsz) for samples of size one sampling method as proposed in Singh and Ye (Proc. ASA, SRM, 2016). It also provides the option to draw a sample by simple random (srs) sampling method or the systematic (sys) sampling method. Under the rsz sampling
Sample Size Estimation for Stratified Sampling Design • Sample size estimation for stratified sampling is difficult in practice, not for the complexity of sample size formula. • Sample size estimation depends on variance estimation. Consider the variance of a mean for a variable y: h h h h h H h h h h h h h H h h h h h h h H h h h str str N With simple random sampling and no stratification in the sample design, the selection probability is the same for all units in the sample. In this sample, the selection probability for each customer equals 0.007423, which is the sample size (100) divided by the population size (13,471). The sampling weight equals 134.71 for each customer in the
For information how to draw a stratified random sample, see Stratified Random Sample. Why Use Stata to Randomize? Randomizing in Stata and subsequently preloading the generated data file into the survey software is the preferred method to randomizing in Excel or randomizing in survey software. The main advantages of randomizing in Stata follow: • We are interested in using Stata for survey data analysis • Survey data are collected from a sample of the population of interest • Each observation in the dataset represents multiple observations in the total population • Sample can be drawn in multiple ways: simple random, stratified, etc.
onsider a sampling scenario: we need to draw 300 samples. We may draw 10 clusters ters with 100 elements. We have said earlier, the uster sampling is to reduce costs. Obviously, the 2. nd. 3 clusters. However, as we have shown above, eff. As a result, the first option should be ” essons for Cluster Sampling • Use as many clusters as For information how to draw a stratified random sample, see Stratified Random Sample. Why Use Stata to Randomize? Randomizing in Stata and subsequently preloading the generated data file into the survey software is the preferred method to randomizing in Excel or randomizing in survey software. The main advantages of randomizing in Stata follow:
Downloadable! gsample draws a random sample from the data in memory. Simple random sampling (SRS) is supported, as well as unequal probability sampling (UPS), of which sampling with probabilities proportional to size (PPS) is a special case. Both methods, SRS and UPS/PPS, provide sampling with replacement and sampling without replacement. …\STATA v 12 stratified analysis of K 2x2 tables.doc Page 11 of 14 . ***** 4b) GRAPH – OR & 95% CI: Overall and by Smoking Note – There are fancier ways of doing this, but the syntax can be complicated.
Second, utilizing a stratified sampling method can lead to more efficient statistical estimates (provided that strata are selected based upon relevance to the criterion in question, instead of availability of the samples). Even if a stratified sampling approach does not lead to increased statistical efficiency, such a tactic will not result in In this section, stratification is added to the sample design for the customer satisfaction survey. The sampling frame, which is the list of all customers, is stratified by State and Type. This divides the sampling frame into nonoverlapping subgroups formed from the values of the State and Type variables. Samples are then selected independently
Stratified sampling - not enough observations. Ask Question Asked 7 years, 11 months ago. Active 7 years, 10 months ago. Viewed 2k times 2. 1. What I would like to achieve is get a 10% sample from each group (which is a combination of 2 factors - recency and frequency category). So far I have thought about package sampling and function strata(). Which looks promising but I am getting the Second, utilizing a stratified sampling method can lead to more efficient statistical estimates (provided that strata are selected based upon relevance to the criterion in question, instead of availability of the samples). Even if a stratified sampling approach does not lead to increased statistical efficiency, such a tactic will not result in
An Introduction to Stata for Survey Data Analysis
Disproportionate Stratified Sampling – Healthcare Economist. 1. Sample randomly a percentage of observations from the large dataset (10%) 2. Sample randomly a fixed number of observations from the large dataset (5,000) In our case we know that both should give us about the sample size we want because we know the actual number of observations in the population., Sample Size Estimation for Stratified Sampling Design • Sample size estimation for stratified sampling is difficult in practice, not for the complexity of sample size formula. • Sample size estimation depends on variance estimation. Consider the variance of a mean for a variable y: h h h h h H h h h h h h h H h h h h h h h H h h h str str N.
r Stratified sampling - not enough observations - Stack
Disproportionate Stratified Sampling – Healthcare Economist. Many data sets that social scientists come across use disproportionate stratified sampling. If a subpopulation is small, the survey designers may want to oversample this group. For example, in the Survey of Income and Program Participation (SIPP) poor … https://en.m.wikipedia.org/wiki/Psychometric_software For information how to draw a stratified random sample, see Stratified Random Sample. Why Use Stata to Randomize? Randomizing in Stata and subsequently preloading the generated data file into the survey software is the preferred method to randomizing in Excel or randomizing in survey software. The main advantages of randomizing in Stata follow:.
In stratified sampling, we usually apply specific (identical or different) sampling fractions to different groups (strata) in the population to draw the sample. In STATISTICA, we can draw stratified random samples by using the Random Sampling options. Over-sampling particular strata … Downloadable! gsample draws a random sample from the data in memory. Simple random sampling (SRS) is supported, as well as unequal probability sampling (UPS), of which sampling with probabilities proportional to size (PPS) is a special case. Both methods, SRS and UPS/PPS, provide sampling with replacement and sampling without replacement.
The Stata command sample codifies one approach to choosing a sample without replacement. The concern here is with explaining enough basic ideas that you can produce your own random samples as desired in Stata with a combination of elementary Stata commands. onsider a sampling scenario: we need to draw 300 samples. We may draw 10 clusters ters with 100 elements. We have said earlier, the uster sampling is to reduce costs. Obviously, the 2. nd. 3 clusters. However, as we have shown above, eff. As a result, the first option should be ” essons for Cluster Sampling • Use as many clusters as
With simple random sampling and no stratification in the sample design, the selection probability is the same for all units in the sample. In this sample, the selection probability for each customer equals 0.007423, which is the sample size (100) divided by the population size (13,471). The sampling weight equals 134.71 for each customer in the Stratified Random Sampling: Definition. Stratified random sampling is used when your population is divided into strata (characteristics like male and female or education level), and you want to include the stratum when taking your sample.
2sample— Draw random sample Remarks and examples stata.com Example 1 We have NLSY data on young women aged 14–26 years in 1968 and wish to draw a 10% sample Stratified Sampling. Question 1. (travel agency) Target population: People aged 20-65 years. We can draw a sample of 1000 persons using Stratified sampling.
Downloadable! This program was written primarily for drawing a sample by the randomly split zones (rsz) for samples of size one sampling method as proposed in Singh and Ye (Proc. ASA, SRM, 2016). It also provides the option to draw a sample by simple random (srs) sampling method or the systematic (sys) sampling method. Under the rsz sampling stratified sample) We save the stratified sample in a folder. The name of the data set is stratifiedBMI.dta Fares Qeadan, Ph.D (Department of Internal Medicine Division of Epidemiology, Biostatistics, & Preventive MedicineUniversity of New Mexico Health Sciences Center)Sampling Methods Using STATA September 14, …
06/11/2011 · The total sample is 1751 individuals. Some combinations of these variables are more common than others, so the strata cellsize ranges from 1 to 99. Then if we start and just allocate by 6s within each cell, we randomly allocate 1590/1751 individuals to a treatment or control group – the first part of this stata code does that. The key 11/01/2015 · Hello, I am working with a complex survey dataset currently that has applied a stratified random sampling design. I would like to understand here whether not using svy setting in Stata would lead to wrong analysis or will it yield the same results when the sampling design is taken into account (using svy commands in stata)
Stratified Random Sampling: Definition. Stratified random sampling is used when your population is divided into strata (characteristics like male and female or education level), and you want to include the stratum when taking your sample. Sample Size: Stratified Random Samples. The precision and cost of a stratified design are influenced by the way that sample elements are allocated to strata. How to Assign Sample to Strata. One approach is proportionate stratification. With proportionate stratification, the sample size of each stratum is proportionate to the population size of
For information how to draw a stratified random sample, see Stratified Random Sample. Why Use Stata to Randomize? Randomizing in Stata and subsequently preloading the generated data file into the survey software is the preferred method to randomizing in Excel or randomizing in survey software. The main advantages of randomizing in Stata follow: And this is where stratified sampling comes in. How to do it. In stratified sampling, the population is divided into different sub-groups or strata, and then the subjects are randomly selected from each of the strata. So, in the above example, you would divide the population into different linguistic sub-groups (one of which is Yiddish speakers
onsider a sampling scenario: we need to draw 300 samples. We may draw 10 clusters ters with 100 elements. We have said earlier, the uster sampling is to reduce costs. Obviously, the 2. nd. 3 clusters. However, as we have shown above, eff. As a result, the first option should be ” essons for Cluster Sampling • Use as many clusters as drawing random samples without replacement (there’s a minor detail we’ll have to discuss because runiform() itself produces values drawn with replacement), drawing random samples with replacement (which is easier to do than most people realize), drawing stratified random samples …
Stratified Random Sampling •Sometimes in survey sampling certain amount of information is known about the elements of the popu-lation to be studied. •For instance, information may be available on the geographical location of the area, e.g. if it is an inner city, a suburban or a rural area. Stratified Random Sampling •Sometimes in survey sampling certain amount of information is known about the elements of the popu-lation to be studied. •For instance, information may be available on the geographical location of the area, e.g. if it is an inner city, a suburban or a rural area.
15/02/2019 · Hello everybody, I want to select my sample in STATA 13 based on three stratum variables with 12 stratas in total (size - two stratas; sector - three stratas; intangible intensity - two stratas). The selection should be proportional without replacement . Stata code for Sampling . Introduction This is a basic introduction to the code that can be used for doing design effect and sample size calculations in Stata. There are other options – many samplers use SAS, Excel, or Optimal Design to do their calculations. 2 . Design Effects •In order to calculate design effects for a particular dataset, you first need to define the complex design for
How to do proportionate stratified The Stata Forum
RANDOM SAMPLING IN SAS Using PROC SQL and PROC. What kind of sample is this? A PE professor wants to study the physical fitness levels of 20,000 students enrolled at her university. She obtains a list of all 20,000 students, numbered from 1 to 20,000 and uses a computer random number generator to generate 100 random integers between 1 and 20,000., Draw a sample of size ni from ith ( 1,2,..., )ik stratum using SRS (preferably WOR) independently from each stratum. All the sampling units drawn from each stratum will constitute a stratified sample of size 1. k i i nn Difference between stratified and cluster sampling schemes In stratified sampling, the strata are constructed such that they are within homogeneous and among heterogeneous. In.
r Stratified random sampling from data frame - Stack
RSZ Stata module to draw a stratified simple random. Stratified Random Sampling: Definition. Stratified random sampling is used when your population is divided into strata (characteristics like male and female or education level), and you want to include the stratum when taking your sample., …\STATA v 12 stratified analysis of K 2x2 tables.doc Page 11 of 14 . ***** 4b) GRAPH – OR & 95% CI: Overall and by Smoking Note – There are fancier ways of doing this, but the syntax can be complicated..
ex: Automobiles are coming off an assembly line. It is decided to draw a systematic sample for a detailed check of the steering system. The starting point will be the … onsider a sampling scenario: we need to draw 300 samples. We may draw 10 clusters ters with 100 elements. We have said earlier, the uster sampling is to reduce costs. Obviously, the 2. nd. 3 clusters. However, as we have shown above, eff. As a result, the first option should be ” essons for Cluster Sampling • Use as many clusters as
With simple random sampling and no stratification in the sample design, the selection probability is the same for all units in the sample. In this sample, the selection probability for each customer equals 0.007423, which is the sample size (100) divided by the population size (13,471). The sampling weight equals 134.71 for each customer in the • We are interested in using Stata for survey data analysis • Survey data are collected from a sample of the population of interest • Each observation in the dataset represents multiple observations in the total population • Sample can be drawn in multiple ways: simple random, stratified, etc.
The MEPS is a stratified, multistage probability cluster sample. The data constitute 12583 females who participated in the household component of MEPS. The population was first stratified into 203 geographical regions, known as strata, within each stratum, the geographical region was subdivided into segments, where an area is composed of And this is where stratified sampling comes in. How to do it. In stratified sampling, the population is divided into different sub-groups or strata, and then the subjects are randomly selected from each of the strata. So, in the above example, you would divide the population into different linguistic sub-groups (one of which is Yiddish speakers
06/11/2011 · The total sample is 1751 individuals. Some combinations of these variables are more common than others, so the strata cellsize ranges from 1 to 99. Then if we start and just allocate by 6s within each cell, we randomly allocate 1590/1751 individuals to a treatment or control group – the first part of this stata code does that. The key UNITED NATIONS SECRETARIAT ESA/STAT/AC.93/5 Statistics Division 03 November 2003 English only Expert Group Meeting to Review the Draft Handbook on Designing of Household Sample Surveys 3-5 December 2003 D R A F T Construction and use of sample weights* by Ibrahim S. Yansaneh** * This document is being issued without formal editing. ** The views expressed in this paper are those of the …
ex: Automobiles are coming off an assembly line. It is decided to draw a systematic sample for a detailed check of the steering system. The starting point will be the … Next, we will set the seed so that the results are replicable. If you do not set a seed and you run the code a second time, you will get slightly different results because a different sample will be used. To draw the sample, we will use the sample command.
15/02/2019 · Hello everybody, I want to select my sample in STATA 13 based on three stratum variables with 12 stratas in total (size - two stratas; sector - three stratas; intangible intensity - two stratas). The selection should be proportional without replacement . stratified sample) We save the stratified sample in a folder. The name of the data set is stratifiedBMI.dta Fares Qeadan, Ph.D (Department of Internal Medicine Division of Epidemiology, Biostatistics, & Preventive MedicineUniversity of New Mexico Health Sciences Center)Sampling Methods Using STATA September 14, …
11/01/2015 · Hello, I am working with a complex survey dataset currently that has applied a stratified random sampling design. I would like to understand here whether not using svy setting in Stata would lead to wrong analysis or will it yield the same results when the sampling design is taken into account (using svy commands in stata) Many data sets that social scientists come across use disproportionate stratified sampling. If a subpopulation is small, the survey designers may want to oversample this group. For example, in the Survey of Income and Program Participation (SIPP) poor …
In stratified sampling, we usually apply specific (identical or different) sampling fractions to different groups (strata) in the population to draw the sample. In STATISTICA, we can draw stratified random samples by using the Random Sampling options. Over-sampling particular strata … Stratified Sampling. Question 1. (travel agency) Target population: People aged 20-65 years. We can draw a sample of 1000 persons using Stratified sampling.
15/02/2019 · Hello everybody, I want to select my sample in STATA 13 based on three stratum variables with 12 stratas in total (size - two stratas; sector - three stratas; intangible intensity - two stratas). The selection should be proportional without replacement . Draw a sample of size ni from ith ( 1,2,..., )ik stratum using SRS (preferably WOR) independently from each stratum. All the sampling units drawn from each stratum will constitute a stratified sample of size 1. k i i nn Difference between stratified and cluster sampling schemes In stratified sampling, the strata are constructed such that they are within homogeneous and among heterogeneous. In
19/01/2013 · 5-Minute tutorial on how to create a stratified random sample in Excel. You are here: Home Sampling SPSS Sampling Tutorials Draw a Stratified Random Sample “I have 5 groups of 10 cases in my data. How can I draw a stratified random sample from these cases? That is, from groups 1 through 5 I'd like to draw exactly 5, 4, 5, 6 and …
PROC SURVEYSELECT Stratified Sampling SAS/STAT(R) 9.22
How can I draw a random sample of my data? Stata FAQ. Next, we will set the seed so that the results are replicable. If you do not set a seed and you run the code a second time, you will get slightly different results because a different sample will be used. To draw the sample, we will use the sample command., UNITED NATIONS SECRETARIAT ESA/STAT/AC.93/5 Statistics Division 03 November 2003 English only Expert Group Meeting to Review the Draft Handbook on Designing of Household Sample Surveys 3-5 December 2003 D R A F T Construction and use of sample weights* by Ibrahim S. Yansaneh** * This document is being issued without formal editing. ** The views expressed in this paper are those of the ….
Stratified Random Sampling UC3M
Stratiп¬Ѓed Random Sampling UC3M. STRATIFIED SAMPLING Jeff Wooldridge Michigan State University LABOUR Lectures, EIEF October 18-19, 2011 1. The Basic Methodology 2. Regression Models 3. Nonlinear Models 4. General Treatment of Exogenous Stratification 1. 1. The Basic Methodology ∙With stratified sampling, some segments of the population are overrepresented or underrepresented by the sampling scheme. If we know enough https://en.m.wikipedia.org/wiki/Psychometric_software 15/02/2019 · Hello everybody, I want to select my sample in STATA 13 based on three stratum variables with 12 stratas in total (size - two stratas; sector - three stratas; intangible intensity - two stratas). The selection should be proportional without replacement ..
In this section, stratification is added to the sample design for the customer satisfaction survey. The sampling frame, which is the list of all customers, is stratified by State and Type. This divides the sampling frame into nonoverlapping subgroups formed from the values of the State and Type variables. Samples are then selected independently drawing random samples without replacement (there’s a minor detail we’ll have to discuss because runiform() itself produces values drawn with replacement), drawing random samples with replacement (which is easier to do than most people realize), drawing stratified random samples …
Downloadable! gsample draws a random sample from the data in memory. Simple random sampling (SRS) is supported, as well as unequal probability sampling (UPS), of which sampling with probabilities proportional to size (PPS) is a special case. Both methods, SRS and UPS/PPS, provide sampling with replacement and sampling without replacement. STRATIFIED SAMPLING Jeff Wooldridge Michigan State University LABOUR Lectures, EIEF October 18-19, 2011 1. The Basic Methodology 2. Regression Models 3. Nonlinear Models 4. General Treatment of Exogenous Stratification 1. 1. The Basic Methodology ∙With stratified sampling, some segments of the population are overrepresented or underrepresented by the sampling scheme. If we know enough
Select whether or not to apply the case selection conditions (if they exist) for the input data file, prior to drawing the stratified random sample. Select No to draw the sample from all cases (observations); select Yes to draw the sample from selected (via the case selection conditions) cases … 02/03/2017 · In this 5 minute Stata segment, I introduce the use of the "sample" command for taking simple random samples in Stata. Other commands introduced include the "count" command and the "set seed" command.
For information how to draw a stratified random sample, see Stratified Random Sample. Why Use Stata to Randomize? Randomizing in Stata and subsequently preloading the generated data file into the survey software is the preferred method to randomizing in Excel or randomizing in survey software. The main advantages of randomizing in Stata follow: 19/01/2013 · 5-Minute tutorial on how to create a stratified random sample in Excel.
drawing random samples without replacement (there’s a minor detail we’ll have to discuss because runiform() itself produces values drawn with replacement), drawing random samples with replacement (which is easier to do than most people realize), drawing stratified random samples … Draw a sample of size ni from ith ( 1,2,..., )ik stratum using SRS (preferably WOR) independently from each stratum. All the sampling units drawn from each stratum will constitute a stratified sample of size 1. k i i nn Difference between stratified and cluster sampling schemes In stratified sampling, the strata are constructed such that they are within homogeneous and among heterogeneous. In
Draw a sample of size ni from ith ( 1,2,..., )ik stratum using SRS (preferably WOR) independently from each stratum. All the sampling units drawn from each stratum will constitute a stratified sample of size 1. k i i nn Difference between stratified and cluster sampling schemes In stratified sampling, the strata are constructed such that they are within homogeneous and among heterogeneous. In In this section, stratification is added to the sample design for the customer satisfaction survey. The sampling frame, which is the list of all customers, is stratified by State and Type. This divides the sampling frame into nonoverlapping subgroups formed from the values of the State and Type variables. Samples are then selected independently
Stratified sampling - not enough observations. Ask Question Asked 7 years, 11 months ago. Active 7 years, 10 months ago. Viewed 2k times 2. 1. What I would like to achieve is get a 10% sample from each group (which is a combination of 2 factors - recency and frequency category). So far I have thought about package sampling and function strata(). Which looks promising but I am getting the Downloadable! This program was written primarily for drawing a sample by the randomly split zones (rsz) for samples of size one sampling method as proposed in Singh and Ye (Proc. ASA, SRM, 2016). It also provides the option to draw a sample by simple random (srs) sampling method or the systematic (sys) sampling method. Under the rsz sampling
2sample— Draw random sample Remarks and examples stata.com Example 1 We have NLSY data on young women aged 14–26 years in 1968 and wish to draw a 10% sample Stratified Random Sampling •Sometimes in survey sampling certain amount of information is known about the elements of the popu-lation to be studied. •For instance, information may be available on the geographical location of the area, e.g. if it is an inner city, a suburban or a rural area.
• We are interested in using Stata for survey data analysis • Survey data are collected from a sample of the population of interest • Each observation in the dataset represents multiple observations in the total population • Sample can be drawn in multiple ways: simple random, stratified, etc. You are here: Home Sampling SPSS Sampling Tutorials Draw a Stratified Random Sample “I have 5 groups of 10 cases in my data. How can I draw a stratified random sample from these cases? That is, from groups 1 through 5 I'd like to draw exactly 5, 4, 5, 6 and …
See the function strata from the package sampling. The function selects stratified simple random sampling and gives a sample as a result. Extra two columns are added - inclusion probabilities (Prob) and strata indicator (Stratum). UNITED NATIONS SECRETARIAT ESA/STAT/AC.93/5 Statistics Division 03 November 2003 English only Expert Group Meeting to Review the Draft Handbook on Designing of Household Sample Surveys 3-5 December 2003 D R A F T Construction and use of sample weights* by Ibrahim S. Yansaneh** * This document is being issued without formal editing. ** The views expressed in this paper are those of the …
Second, utilizing a stratified sampling method can lead to more efficient statistical estimates (provided that strata are selected based upon relevance to the criterion in question, instead of availability of the samples). Even if a stratified sampling approach does not lead to increased statistical efficiency, such a tactic will not result in In this section, stratification is added to the sample design for the customer satisfaction survey. The sampling frame, which is the list of all customers, is stratified by State and Type. This divides the sampling frame into nonoverlapping subgroups formed from the values of the State and Type variables. Samples are then selected independently
