Undestanding truncation distance

[riccardo...@gmail.com]

Hi everybody,

Sorry for the stupid question but I would like to have a clarification on the truncation distance. When in the ds function I specify for example "truncation = "20%" what does it mean practically? Are 20% of the observations excluded? Or something else?

Thank you very much.

Kind Regards

[Eric Rexstad]

Riccardo

Specifying a percentage for the truncation argument carries this meaning. Rank detections in ascending order of detection distance. Identify the distance at which 20% of the detections are at greater distances. Exclude from your analysis those detections at distances greater than this value.

Why is truncation performed? Because we are trying to fit models to the process that gives rise to detections. At large distances, the process dictates that detections are unlikely, but some detections arise by chance. Truncation excludes those detections that are more a result of chance than a result of the process we are trying to model.

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From: distance...@googlegroups.com <distance...@googlegroups.com> on behalf of riccardo...@gmail.com <riccardo...@gmail.com>
Sent: 23 May 2023 19:30
To: distance-sampling <distance...@googlegroups.com>
Subject: [distance-sampling] Undestanding truncation distance

 

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[riccardo...@gmail.com]

Dear Eric,

Thank you for your message! I appreciate your help and the explanations you provided. Your assistance has been valuable in helping me understand the concepts better. I'm grateful for your time and support.

Best regards, Riccardo