Generates area estimates by domain (and estimation unit). Calculations are based on Scott et al. 2005 ('the green-book') for mapped forest inventory plots. The non-ratio estimator for estimating area by stratum and domain is used. Plots that are totally nonsampled are excluded from estimation dataset. Next, an adjustment factor is calculated by strata to adjust for nonsampled (nonresponse) conditions that have proportion less than 1. The attribute is the proportion of the plot which is divided by the adjustment factor, and averaged by stratum. Strata means are combined using the strata weights and then expanded to area using the total land area in the population.
modGBarea(
GBpopdat,
landarea = "FOREST",
pcfilter = NULL,
rowvar = NULL,
colvar = NULL,
sumunits = TRUE,
returntitle = FALSE,
savedata = FALSE,
table_opts = NULL,
title_opts = NULL,
savedata_opts = NULL,
gui = FALSE,
...
)A list with estimates with percent sampling error for rowvar (and colvar). If sumunits=TRUE or unitvar=NULL and colvar=NULL, one data frame is returned. Otherwise, a list object is returned with the following information. If savedata=TRUE, all data frames are written to outfolder.
Data frame. Area estimates, in area units (e.g., acres), by rowvar, colvar (and estimation unit). If sumunits=TRUE or one estimation unit and colvar=NULL, or allin1=TRUE, estimates and percent sampling error are in one data frame.
Data frame. Percent sampling errors (Confidence level 68 for estimates by rowvar and colvar (and estimation unit).
List. If returntitle=TRUE a list with table title(s). The list contains one title if est and pse are in the same table and two titles if est and pse are in separate tables. Row and column tables are also included in list.
List. If rawdata=TRUE, a list including the processing data used for estimation including: number of plots and conditions; stratification information; and 1 to 8 tables with calculated values for table cells and totals (See processing data below).
Raw data
Table. Number of plots by plot status (e.g., sampled forest on plot, sampled nonforest, nonsampled).
DF. Number of conditions by condition status (forest land, nonforest land, noncensus water, census water, nonsampled).
DF. Area by estimation unit.
DF. Condition-level area expansion factors.
DF. Final data table used for estimation.
Data frame. Strata information by estimation unit.
| Variable | Description | |
| unitvar | estimation unit | |
| strvar | stratum value | |
| strwtvar | number of pixels by strata and estimation unit | |
| n.strata | number of plots in strata (after totally nonsampled plots removed) | |
| n.total | number of plots for estimation unit | |
| strwt | proportion of area (or plots) by strata and estimation unit (strata weight) | |
| CONDPROP_UNADJ_SUM | summed condition proportion by strata and estimation unit | |
| CONDPROP_ADJFAC | adjusted condition proportion by strata after nonresponse plots removed | |
| AREA | total area for estimation unit | |
| CONDPROP_ADJFAC | average area |
Data frames. Separate data frames containing calculated variables used in estimation process. The number of processing tables depends on the input parameters. The tables include: total by estimation unit (unit.totest); rowvar totals (unit.rowest), colvar totals, if not NULL (unit.colvar); and a combination of rowvar and colvar, if colvar is not NULL (unit.grpvar). If sumunits=TRUE, the raw data for the summed estimation units are also included (totest, rowest, colest, grpest, respectively). These tables do not included estimate proportions (nhat and nhat.var).
The data frames include the following information:
| Variable | Description | |
| nhat | estimate proportion of land | |
| nhat.var | variance estimate of estimated proportion of land | |
| NBRPLT.gt0 | Number of non-zero plots used in estimates | |
| AREA | total area for estimation unit | |
| est | estimated area of land nhat*areavar | |
| est.var | variance estimate of estimate acres of land nhat.var*areavar^2 | |
| est.se | standard error of estimated area of land sqrt(est.var) | |
| est.cv | coefficient of variation of estimated area of land est.se/est | |
| pse | percent sampling error of estimate est.cv*100 | |
| CI99left | left tail of 99 percent confidence interval for estimated area | |
| CI99right | right tail of 99 percent confidence interval for estimated area | |
| CI95left | left tail of 95 percent confidence interval for estimated area | |
| CI95right | right tail of 95 percent confidence interval for estimated area | |
| CI67left | left tail of 67 percent confidence interval for estimated area | |
| CI67right | right tail of 67 percent confidence interval for estimated area |
savedata
if savedata=TRUE...
tables with estimate and percent standard error will be written as *csv files to outfolder. if rawdata=TRUE, the rawdata will be output to the outfolder in a folder named rawdata (if raw_fmt="csv") or a database in the outfolder, if (raw_fmt != "csv").
if outfn.pre is not null...
a prefix is added to output files if raw_fmt = 'csv', prefix is added to file names in rawdata folder if raw_fmt != 'csv', prefix is added to dsn name
List. Population data objects returned from modGBpop().
String. The sample area filter for estimates ("ALL", "FOREST", "TIMBERLAND"). If landarea=FOREST, filtered to COND_STATUS_CD = 1; If landarea=TIMBERLAND, filtered to SITECLCD in(1:6) and RESERVCD = 0.
String. A filter for plot or cond attributes (including pltassgn). Must be R logical syntax.
String. Name of row domain variable in cond. If only one domain, rowvar = domain variable. If more than one domain, include colvar. If no domain, rowvar = NULL.
String. Name of column domain variable in cond.
Logical. If TRUE, estimation units are summed and returned in one table.
Logical. If TRUE, returns title(s) of the estimation table(s).
Logical. If TRUE, saves table(s) to outfolder.
List. See help(table_options()) for a list of options.
List. See help(title_options()) for a list of options.
List. See help(savedata_options()) for a list of options. Only used when savedata = TRUE.
Logical. If gui, user is prompted for parameters.
Parameters for modGBpop() if GBpopdat is NULL.
Tracey S. Frescino, Paul L. Patterson, Elizabeth A. Freeman
If variables are NULL, then it will prompt user to input variables.
Necessary variables:
| Data | Variable | Description | |
| cond | cuniqueid | Unique identifier for each plot, to link to pltassgn (ex. PLT_CN). | |
| CONDID | Unique identifier of each condition on plot. Set CONDID=1, if only 1 condition per plot. | ||
| CONDPROP_UNADJ | Unadjusted proportion of condition on each plot. Set CONDPROP_UNADJ=1, if only 1 condition per plot. | ||
| COND_STATUS_CD | Status of each forested condition on plot (i.e. accessible forest, nonforest, water, etc.) | ||
| NF_COND_STATUS_CD | If ACI=TRUE. Status of each nonforest condition on plot (i.e. accessible nonforest, nonsampled nonforest) | ||
| SITECLCD | If landarea=TIMBERLAND. Measure of site productivity. | ||
| RESERVCD | If landarea=TIMBERLAND. Reserved status. | ||
| pltassgn | puniqueid | Unique identifier for each plot, to link to cond (ex. CN). | |
| STATECD | Identifies state each plot is located in. | ||
| INVYR | Identifies inventory year of each plot. | ||
| PLOT_STATUS_CD | Status of each plot (i.e. sampled, nonsampled). If not included, all plots are assumed as sampled. |
For available reference tables: sort(unique(FIESTAutils::ref_codes$VARIABLE))
Scott, Charles T.; Bechtold, William A.; Reams, Gregory A.; Smith, William D.; Westfall, James A.; Hansen, Mark H.; Moisen, Gretchen G. 2005. Sample-based estimators used by the Forest Inventory and Analysis national information management system. Gen. Tech. Rep. SRS-80. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station, p.53-77.
# \donttest{
GBpopdat <- modGBpop(
popTabs = list(cond = FIESTA::WYcond,
tree = FIESTA::WYtree,
seed = FIESTA::WYseed),
popTabIDs = list(cond = "PLT_CN"),
pltassgn = FIESTA::WYpltassgn,
pltassgnid = "CN",
pjoinid = "PLT_CN",
unitarea = FIESTA::WYunitarea,
unitvar = "ESTN_UNIT",
strata = TRUE,
stratalut = WYstratalut,
strata_opts = strata_options(getwt = TRUE)
)
forest_area <- modGBarea(
GBpopdat = GBpopdat,
landarea = "FOREST",
sumunits = TRUE,
)
str(forest_area, max.level = 1)
forest_area_by_forest_type <- modGBarea(
GBpopdat = GBpopdat,
landarea = "FOREST",
rowvar = "FORTYPCD",
sumunits = TRUE
)
str(forest_area_by_forest_type, max.level = 1)
# }
Run the code above in your browser using DataLab