SpotSampling (version 0.1.0)

Spot: SPOT method

Description

Select spatio-temporal samples of fixed size and well spread out in space at each wave. The pivotal method is used to obtain spread samples. It provides optimal time rotation of the selected sample using the systematic sampling method.

Usage

Spot(pik, coord, EPS = 1e-08, comment = TRUE)

Arguments

pik

a matrix of temporal inclusion probabilities. Columns of pik correspond to the waves, and rows correspond to the units. Inclusion probabilities can be totally unequal.

coord

a matrix that contains spatial coordinates in columns. The number of columns can be more than two. Matrix rows correspond to the units.

EPS

a tolerance parameter. Default value is 1e-8.

comment

a comment is written during the execution if comment is TRUE (default value).

Value

a matrix that contains temporal samples. This is the update of pik and contains only 0s and 1s that indicates if a unit is selected or not at each wave.

References

Quenouille, M. H. (1949). Approximate Tests of Correlation in time-Series. Royal Statistical Society, Series B Vol. 11, No. 1 (1949), pp. 68-84.

Grafstrom, A., Lundstrom, N. L. P., and Schelin, L. (2012). Spatially balanced sampling through the pivotal method. Biometrics, 68(2):514-520.

See Also

SystematicDesign, ReducedSamplecube.

Examples

# NOT RUN {
## Coordinates in two dimensions of 4 units ##
coord <- matrix(c(0.5,0.6,0.2,0.3,0.8,0.9,0.4,0.7), ncol=2)
## Temporal inclusion probabilities with 3 waves and 4 units ##
pik <- matrix(c(0.6,0.3,0.3,
                0.2,0.4,0.9,
                0.3,0.2,0.5,
                0.9,0.1,0.3), ncol = 3, byrow = TRUE)
## SPOT method ##
Spot(pik, coord, EPS = 1e-6)

# }