The data consist of simulated variables, including an individual-level covariate (x1) and two area-level covariates (x2, x3) available at two
different spatial scales (ss1, ss2). The data are in the form of a 3-D or stacked array, where each stack represents a particular level of
covariates, including spatial scale. The first stack contains the individual-level variable; the second and third stacks contain the area-level
variables at the ss1 and ss2 levels, respectively. Note that in cases where values are only present for a covariate at certain levels, that
covariate is assigned missing values at all other levels.
References
Grant LP, Gennings C, Wheeler, DC. (2015). Selecting spatial scale of covariates in regression models of environmental exposures.
Cancer Informatics, 14(S2), 81-96. doi: 10.4137/CIN.S17302