This function calculates the variance-covariance estimate for the cell and marginal totals used to calculate the relative risk estimate. Either the simple random sampling (SRS) variance estimator or the local mean variance estimator is calculated, which is subject to user control. The SRS variance estimator uses the independent random sample approximation to calculate joint inclusion probabilities. The function can accomodate single-stage and two-stage samples.
relrisk.var(response, stressor, response.levels, stressor.levels, wgt, x,
y, 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 categorical response variable.
Vector of the categorical stressor variable.
Vector of category values (levels) for the categorical response variable, where the first level is used for calculating the relative risk estimate. If response.levels equals NULL, then values "Poor" and "Good" are used for the first level and second level of the response variable, respectively. The default is NULL.
Vector of category values (levels) for the categorical stressor variable, where the first level is used for calculating the numerator of the relative risk estimate and the second level is used for calculating the denominator of the estimate. If stressor.levels equals NULL, then values "Poor" and "Good" are used for the first level and second level of the stressor variable, respectively. The default is NULL.
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 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.
Object in list format composed of a vector named varest, which contains the variance-covariance estimate, 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