modGBp2veg: Green-Book module - Generate area estimates.

In FIESTA: Forest Inventory Estimation and Analysis

Green-Book module - Generate area estimates.

Description

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.

Usage

modGBp2veg(
  GBpopdat = NULL,
  p2vegtype = "str",
  peracre = FALSE,
  landarea = "FOREST",
  pcfilter = NULL,
  vfilter = NULL,
  rowvar = NULL,
  colvar = NULL,
  sumunits = TRUE,
  returntitle = FALSE,
  savedata = FALSE,
  table_opts = NULL,
  title_opts = NULL,
  savedata_opts = NULL,
  gui = FALSE,
  ...
)

Arguments

GBpopdat	List. Population data objects returned from modGBpop().
p2vegtype	String. Type of p2veg estimate ('str', 'spp').
peracre	Logical. If TRUE, generates per-acre estimates.
landarea	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.
pcfilter	String. A filter for plot or cond attributes (including pltassgn). Must be R logical syntax.
vfilter	String. A filter for the P2 vegetation table used for estimate. Must be R logical syntax.
rowvar	String. Name of row domain variable in cond (e.g., 'FORTYPCD') or P2VEG_SUBP_STRUCTURE (e.g., 'GROWTH_HABIT_CD', 'LAYER') or P2VEG_SUBPLOT_SPP (e.g., 'VEG_FLDSPCD', 'VEG_SPCD', 'GROWTH_HABIT_CD', 'LAYER'). If only one domain, rowvar = domain variable. If more than one domain, include colvar. If no domain, rowvar = NULL.
colvar	String. Name of column domain variable in cond.
sumunits	Logical. If TRUE, estimation units are summed and returned in one table.
returntitle	Logical. If TRUE, returns title(s) of the estimation table(s).
savedata	Logical. If TRUE, saves table(s) to outfolder.
table_opts	List. See help(table_options()) for a list of options.
title_opts	List. See help(title_options()) for a list of options.
savedata_opts	List. See help(savedata_options()) for a list of options. Only used when savedata = TRUE.
gui	Logical. If gui, user is prompted for parameters.
...	Parameters for modGBpop() if GBpopdat is NULL.

Details

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))

Value

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.

est	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.
pse	Data frame. Percent sampling errors (Confidence level 68 unit).
titlelst	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.
raw	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

plotsampcnt	Table. Number of plots by plot status (e.g., sampled forest on plot, sampled nonforest, nonsampled).
condsampcnt	DF. Number of conditions by condition status (forest land, nonforest land, noncensus water, census water, nonsampled).
unitarea	DF. Area by estimation unit.
expcondtab	DF. Condition-level area expansion factors.
domdat	DF. Final data table used for estimation.
stratdat	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

processing data

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

Note

ADJUSTMENT FACTOR:
The adjustment factor is necessary to account for nonsampled conditions. It is calculated for each estimation unit by strata by summing the unadjusted condition proportions (CONDPROP_UNADJ) and dividing by the number of plots in the strata/estimation unit.

If ACI=FALSE, only nonsampled forest conditions are accounted for in the adjustment factor.
If ACI=TRUE, the nonsampled nonforest conditions are removed as well and accounted for in adjustment factor. This is if you are interested in estimates for all lands or nonforest lands in the All-Condition-Inventory.

STRATA:
Stratification is used to reduce variance in population estimates by partitioning the population into homogenous classes (strata), such as forest and nonforest. For stratified sampling methods, the strata sizes (weights) must be either known or estimated. Remotely-sensed data is often used to generate strata weights with proporation of pixels by strata. If stratification is desired (strata=TRUE), the required data include: stratum assignment for the center location of each plot, stored in either pltassgn or cond; and a look-up table with the area or proportion of the total area of each strata value by estimation unit, making sure the name of the strata (and estimation unit) variable and values match the plot assignment name(s) and value(s).

sumunits:
An estimation unit is a population, or area of interest, with known area and number of plots. Individual counties or combined Super-counties are common estimation units for FIA. An estimation unit may also be a subpopulation of a larger population (e.g., Counties within a State). Subpopulations are mutually exclusive and independent within a population, therefore estimated totals and variances are additive. For example, State-level estimates are generated by summing estimates from all subpopulations within the State (Bechtold and Patterson. 2005. Chapter 2). Each plot must be assigned to only one estimation unit.

If sumunits=TRUE, estimates are generated by estimation unit, summed together, and returned as one estimate. If rawdata=TRUE, estimates by individual estimation unit are also returned.

If sumunits=FALSE, estimates are generated and returned by estimation unit as one data frame. If savedata=TRUE, a separate file is written for each estimation unit.

stratcombine:
If TRUE and less than 2 plots in any one estimation unit, all estimation units with 10 or less plots are combined. The current method for combining is to group the estimation unit with less than 10 plots with the estimation unit following in consecutive order (numeric or alphabetical), restrained by survey unit (UNITCD) if included in dataset, and continuing until the number of plots equals 10. If there are no estimation units following in order, it is combined with the estimation unit previous in order.

rowlut/collut:
There are several objectives for including rowlut/collut look-up tables: 1) to include descriptive names that match row/column codes in the input table; 2) to use number codes that match row/column names in the input table for ordering rows; 3) to add rows and/or columns with 0 values for consistency. No duplicate names are allowed.

Include 2 columns in the table:
1-the merging variable with same name as the variable in the input merge table;
2-the ordering or descriptive variable.
If the ordering variable is the rowvar/colvar in the input table and the descriptive variable is in rowlut/collut, set row.orderby/col.orderby equal to rowvar/colvar. If the descriptive variable is the rowvar/colvar in the input table, and the ordering code variable is in rowlut/collut, set row.orderby/col.orderby equal to the variable name of the code variable in rowlut/collut.

Author(s)

Tracey S. Frescino, Paul L. Patterson, Elizabeth A. Freeman

References

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.

FIESTA documentation built on Nov. 22, 2023, 1:07 a.m.