I am trying to analyze distance data that were collected via line-transect survey method. I was wondering, when you include a categorical covariate in the formula for your key function, do you need to make sure that a value for that variable is specified for those transects that did NOT result in any observations (in the flatfile)?.
In my mind, it should seem to make a difference in the hypothetical case of one category resulting in many transects with >= 1 detection, and another category resulting in many transects without any detection.
Hi Brian, yes you should always include zero value transects as rows in your data. Otherwise you would overestimate your count. If you need any clarification let me know!
Hi Brian, yes you should always include zero value transects as rows in your data. Otherwise you would overestimate your count. If you need any clarification let me know!
Agreeing with Richard, plus: knowing the covariate values where zero counts are observed may be particularily important to understand/explain your results.
I don't know if anything more could be added To Richard's answer. Absence is as important as Presence.
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