Skip to main content
U.S. flag

An official website of the United States government

Wild horse aerial double observer survey analysis R script

November 22, 2019

This R file estimates horse abundance by analyzing data from simultaneous double-observer aerial surveys. The code follows analytical procedures established by Dr. Bruce Lubow, the statistician contracted for many years by Bureau of Land Management (BLM). Field data collection techniques are described in the Standard Operating Procedures (SOPs), which is a separate document.

Download the files "SDO_RMark_template.R" and "Example_data.csv" to the same directory. Open R and make this the working directory with File | Change dir.

Install the required packages "htmltools", "zoo", and "RMark". Make sure RMark is updated to the latest version if you already have it installed; earlier versions contained a bug that caused the script to crash.

Before running the script in R, expand the console window to best display results from tables in your web browser. Once you run the script, it pauses until you left click to move past figures. The pauses allow you time to inspect

Tables are also saved in your working directory as .csv files. The R script outputs a text file (Report.txt) that is a rough first draft of the Memorandum, which is the report sent to BLM. All tables associated with the report are named "Report_TableX.csv"; the code also saves various other .csv tables with more detailed results, and a histogram of bootstrap results.

Publication Year 2019
Title Wild horse aerial double observer survey analysis R script
DOI 10.5066/P946MHTZ
Authors Lars S Ekernas
Product Type Software Release
Record Source USGS Digital Object Identifier Catalog
USGS Organization Fort Collins Science Center