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Compare Two FAO Data Releases

Source: R/compare_releases.R
compare_releases.Rd

This function compares two releases of the FAO Global Capture Production data record by record (country, species item, fishing area and year) and lists the historical data that were revised between them: records whose catch changed, records added for years the older release already covered, and records removed. It summarises the revisions by year and by country and shows how the total catch of each year changed.

Usage

compare_releases(
  old = NULL,
  new = NULL,
  area_name = NULL,
  country_name = NULL,
  tolerance = 0.5,
  top_n = 10,
  plot = TRUE,
  table = TRUE,
  lang = NULL,
  pptx = getOption("faofishingreport.pptx", FALSE),
  plot_show = fao_setting("plot_show"),
  label = NULL,
  data_dir = fao_data_dir()
)

Arguments

old, new

The releases to compare, e.g. "2025.1.0" and "2026.1.0", or "bundled" for the data bundled with the package. Default is the newest release available on this computer for new, and the one before it for old.

area_name, country_name

Optional FAO fishing areas and countries to compare. Default is NULL, all.

tolerance

Changes of at most this many tonnes are ignored. Default is 0.5 (rounding).

top_n

The number of countries with the largest revisions in the country chart. Default is 10.

plot

A logical value. If TRUE (default), charts are saved in figures/png/summary/.

table

A logical value. If TRUE (default), tables are saved in tables/.

lang

The language of the chart text and names: "en" (English), "zh" (Chinese) or "both" (Chinese and English). Default is NULL, which uses the language set with fao_settings() ("en" unless changed).

pptx

A logical value. If TRUE, charts are also saved as editable PowerPoint files in figures/pptx/summary/. Default is FALSE, which can be changed for all functions with fao_settings(pptx = TRUE).

plot_show

A logical value. If TRUE, each chart is also drawn in the plot window (e.g. the Plots pane of RStudio) as it is saved, to look at it at once. Default is FALSE, which can be changed for all functions with fao_settings(plot_show = TRUE). The charts are saved as files (plot = TRUE) either way.

label

The name used in the output file names. Default is the fishing area (or the country) of the data.

data_dir

The directory where downloaded releases are stored. Default is fao_data_dir().

Value

Invisibly, a list with by_year (catch in both releases and the revisions of each year), by_country (revisions by country, without reclassified records), records (every revised, added, removed or reclassified record) and releases (the two releases compared).

Details

FAO revises earlier years when countries send corrected or more complete data (Garibaldi 2012). Zeller and Pauly (2018) call "presentist bias" the practice of applying improvements in reporting to recent years only, without revising the earlier years, which makes the time series show an increase that did not happen. Comparing releases shows which years and countries were revised and how far back the revisions reach. No published study has compared successive FishStat releases record by record in this way; the comparison is a tool of this package, and the two papers above give the background.

Releases are compared on the names used by the package (matched through FAO codes when a release is downloaded). A record removed under one species item and added under another with the same country, area, year and catch (e.g. when FAO renames or splits a species item) is marked "reclassified" and is not counted as a revision of the catch. Download older releases first with download_fao_data(version = ...); check_fao_update() lists them.

References

Garibaldi, L. (2012). The FAO global capture production database: a six-decade effort to catch the trend. Marine Policy 36: 760-768. doi:10.1016/j.marpol.2011.10.024

Zeller, D. and Pauly, D. (2018). The 'presentist bias' in time-series data: implications for fisheries science and policy. Marine Policy 90: 14-19. doi:10.1016/j.marpol.2018.01.015

Examples

if (FALSE) { # \dontrun{
download_fao_data(version = "2025.1.0")
compare_releases("2025.1.0", "2026.1.0", lang = "zh")
compare_releases("2025.1.0", "2026.1.0", country_name = "China")
} # }