The function in arena-survey-analysis.R is used to compute statistical results for all (active) area-based quantitative variables in Open Foris (OF) Arena. The list of these variables are shown in Arena's chain-section as shown below:
Currently, only one entity, such as tree in the picture above, can be selected for computing the results.
The script also computes area estimates for given dimensions, either as combination of dimensions or separately. The dimensions are selected in the Arena user-interface (UI), and they can be any categorical, boolean, or taxonomic attribute in the input data, or categorical attribute in the processing chain (such as plot_fra shown above).
The result statistics contain means, totals, and associated standard deviations, variances, confidence intervals, and sample sizes.
The results also contain totals and means over domains, such as strata.
The results will be written into CSV files.
This function can be called in Arena data processing chain, after running 'persist-results.R'.
The OF Arena manual containing the description of the calculation chain is available at https://docs.google.com/document/d/1GWerrExvbdT5oOOlwdkE9pptK4pVbQxwtgaSNPasmKA/view
About this script: The script first creates a list of data frames ('result_cat') for statistical analysis. This is input data for the analysis part. This object contains "per hectare" data summed up to the base unit level, grouped by entities. It contains all categorical, taxonomic and boolean attributes as dimensions.
Required R packages (with dependencies): dplyr, rlang, stringr, tidyr, srvyr, survey. Two-phase sampling: tidyverse, forestinventory
Created by: Lauri Vesa (FAO), Javier Garcia Perez (FAO), Stefano Ricci (FAO), Ramiro Blazquez Gonzalez (FAO), Anibal Cuchietti (FAO)