This function uses the repeat visit sites for two probability surveys to calculate either covariance or correlation estimates of estimated change in resource size in each of a set of categories. Covariance estimates are calculated when the resivit sites have the same survey design weight in both surveys. Correlation estimates are calculated when the revisit sites do not have the same weight in both surveys, in which case the sites are assigned equal weights. The revisitwgt argument controls whether covariance or correlation estimates are calculated. Either the simple random sampling (SRS) variance/covariance estimator or the local mean variance/covariance estimator is calculated, which is subject to user control. The simple random sampling variance/covariance estimator uses the independent random sample approximation to calculate joint inclusion probabilities. The function can accomodate single-stage and two-stage samples. Finite population and continuous population correction factors can be utilized in variance estimation.
changevar.size(catvar.levels, catvar1, catvar2, wgt, x, y, revisitwgt,
size1, size2, stratum.ind, stratum.level, cluster.ind, cluster, wgt1, x1,
y1, pcfactor.ind, pcfsize, N.cluster, stage1size, support, vartype,
warn.ind, warn.df, warn.vec)Vector of the set of categorical response values.
Vector of the response value for each site for survey one.
Vector of the response value for each site for survey two.
Vector of the final adjusted weight (inverse of the sample inclusion probability) for each site, which is either the weight for a single-stage sample or the stage two weight for a two-stage sample.
Vector of x-coordinate for location for each site, which is either the x- coordinate for a single-stage sample or the stage two x-coordinate for a two-stage sample.
Vector of y-coordinate for location for each site, which is either the y- coordinate for a single-stage sample or the stage two y-coordinate for a two-stage sample.
Logical value that indicates whether each repeat visit site has the same survey design weight in the two surveys, where TRUE = the weight for each repeat visit site is the same and FALSE = the weight for each repeat visit site is not the same. When this argument is FALSE, all of the repeat visit sites are assigned equal weights when calculating the covariance component of the change estimate standard error.
The set of category size estimates for survey one.
The set of category size estimates for survey two.
Logical value that indicates whether the sample is stratified, where TRUE = a stratified sample and FALSE = not a stratified sample.
The stratum level.
Logical value that indicates whether the sample is a two- stage sample, where TRUE = a two-stage sample and FALSE = not a two-stage sample.
Vector of the stage one sampling unit (primary sampling unit or cluster) code for each site.
Vector of the final adjusted stage one weight for each site.
Vector of the stage one x-coordinate for location for each site.
Vector of the stage one y-coordinate for location for each site.
Logical value that indicates whether the population correction factor is used during variance estimation, where TRUE = use the population correction factor and FALSE = do not use the factor. To employ the correction factor for a single-stage sample, values must be supplied for arguments pcfsize and support. To employ the correction factor for a two-stage sample, values must be supplied for arguments N.cluster, stage1size, and support.
Size of the resource, which is required for calculation of finite and continuous population correction factors for a single-stage sample. For a stratified sample this argument must be a vector containing a value for each stratum and must have the names attribute set to identify the stratum codes.
The number of stage one sampling units in the resource, which is required for calculation of finite and continuous population correction factors for a two-stage sample. For a stratified sample this variable must be a vector containing a value for each stratum and must have the names attribute set to identify the stratum codes.
Size of the stage one sampling units of a two-stage sample, which is required for calculation of finite and continuous population correction factors for a two-stage sample and must have the names attribute set to identify the stage one sampling unit codes. For a stratified sample, the names attribute must be set to identify both stratum codes and stage one sampling unit codes using a convention where the two codes are separated by the & symbol, e.g., "Stratum 1&Cluster 1".
Vector of the support value for each site - the value one (1) for a site from a finite resource or the measure of the sampling unit associated with a site from a continuous resource, which is required for calculation of finite and continuous population correction factors.
The choice of variance estimator, where "Local" = local mean estimator and "SRS" = SRS estimator.
Logical value that indicates whether warning messages were generated, where TRUE = warning messages were generated and FALSE = warning messages were not generated.
Data frame for storing warning messages.
Vector that contains names of the population type, the subpopulation, and an indicator.
An object in list format composed of a vector named rslt, which contains the covariance or correlation estimates, a logical variable named warn,ind, which is the indicator for warning messges, and a data frame named warn.df, which contains warning messages.
localmean.weightcalculate the weighting matrix for the local mean variance estimator
localmean.covcalculate the variance/covariance matrix using the local mean estimator