Question about point count distance grouping

[Allison F]

The data I am currently working with to estimate abundance with was taken at point counts, but exact distances were not measured. Instead, sightings were grouped into less than 50 m and greater than 50 m. Is there a way to incorporate this into the program? I am new to the program.

Thanks

[Eric Rexstad]

Good morning Allison, welcome to the group.

You can treat the distance data as categorical (two bins 0-50, 50-xxx) rather than exact. However, there are two problems with this. With only two bins, you will be badly hampered in the types of detection function models you can fit to your data (very simple models with only a single parameter). Secondly, it is unlikely that models will fit your data. The first bin is too wide, because there is a lot happening in the first 50m around an observer, not only is detectability changing over that distance but also the number of animals available to be detected is also changing rapidly over the first 50m.

Have a look through our online materials describing analysis of point transect data

https://distancesampling.org/online-course/05-points/pointslanding.html

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From: distance...@googlegroups.com <distance...@googlegroups.com> on behalf of Allison F <allison...@gmail.com>
Sent: 06 October 2025 19:35
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Subject: {Suspected Spam} [distance-sampling] Question about point count distance grouping

 

The data I am currently working with to estimate abundance with was taken at point counts, but exact distances were not measured. Instead, sightings were grouped into less than 50 m and greater than 50 m. Is there a way to incorporate this into the program? I am new to the program.

Thanks

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