Agriculture Reference
In-Depth Information
Fig. 6.8 Selection of rotated panel with a replacement rate of 40 % by using the method of
permanent random numbers ( small circle units selected in time t , large circles units selected in
time t +1, two circles units selected in both the periods)
The coordination of subsequent surveys to obtain the desired overlap is obtained
by shifting the selection, starting from the l h -th unit until the ( n h + l h )-th unit. Here l h
is calculated according to the rate of rotation required for the panel. This selection
criterion, particularly if repeated several
times, always uses the trick that
if
( n h + l h )
N h , the remaining units must be selected from the start to create a kind
of circular ordering. Similar operations can be used to coordinate multiple surveys
instead of multiple periods of the same survey.
Finally, we must point out that this method can be easily extended to extract data
with variable probability
>
π k . In this case, it is sufficient to order on the basis of the
parameter ( R k /
π k ) n, to obtain samples that are more likely to include important units
(SPS, see Sect. 6.4 ).
The following code uses the PRN technique to obtain a rotated panel with a
replacement rate of 40 %. This sample is displayed in Fig. 6.8 .
> set.seed(200694)
> rate < - 0.4
> par(mar ¼ c(1,1,1,1),xaxs ¼ "i",yaxs ¼ "i")
> framecoord < - cbind(framepop[,1:9],R ¼ runif(N),
Search WWH ::




Custom Search