| sqlocpoly {surveyNG} | R Documentation |
This function performs weighted density estimation and smoothing, using the binned local polynomial smoothers in the KernSmooth package.
sqlocpoly(formula, design, bandwidth, M = 401)
formula |
One-sided formula for density estimation, two-sided for smoothing |
design |
sqlsurvey object |
bandwidth |
Smoothing bandwidth |
M |
Number of grid points |
The binning is performed in SQL, so for large data sets the computation time is roughly linear in M and in the number of observations. M should be a few times larger than range(x)/bandwidth, but can often be reduced from the default value.
An object of class svysmooth
sqclus1<-sqlsurvey(id="dnum", fpc="fpc", weights="pw", strata="fpc",
data=system.file("apiclus1.db",package="surveyNG"),
table.name="clus1", key="snum")
dens <- sqlocpoly(~api00, sqclus1, bandwidth=50)
smooth <- sqlocpoly(api00~api99, sqclus1, bandwidth=50)
dens
plot(dens)
plot(smooth)
close(sqclus1)