| getdata {sampling} | R Documentation |
Extracts the observed data from the data frame. The function is used after a sample is drawn.
getdata(data, m)
data |
the data frame or data matrix; its number of rows is N, the population size. |
m |
the vector of the selected units or the sampled data set. |
srswor, UPsystematic, strata,
cluster, mstage
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## Example 1
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# Generates artificial data (a 235X3 matrix with 3 columns: state, region, income).
# The variable 'state' has 2 categories (nc and sc);
# the variable 'region' has 3 categories (1, 2 and 3);
# the variable 'income' is generated using U(0,1) distribution.
data=rbind(matrix(rep("nc",165),165,1,byrow=TRUE),
matrix(rep("sc",70),70,1,byrow=TRUE))
data=cbind.data.frame(data,c(rep(1,100), rep(2,50), rep(3,15), rep(1,30),rep(2,40)),1000*runif(235))
names(data)=c("state","region","income")
# the inclusion probabilities are computed using the variable 'income'
pik=inclusionprobabilities(data$income,20)
# draw a sample s using systematic sampling (sample size is 20)
s=UPsystematic(pik)
# extracts the observed data
getdata(data,s)
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## Example 2
############
# see other examples in 'strata', 'cluster', 'mstage' help