Summary statistic mean and maximum site visits equal??

[Lilo Schultz]

Hi all,

I am relatively new to unmarked and am having some trouble understanding if I am coding something incorrectly or just misinterpreting my results. I am currently doing some occupancy modeling for a few focal mammal species, and when I look at a summary of my detection history made in R, the mean and maximum observations are the same. Here are two examples of separate species:

49 sites Maximum number of observations per site: 12 Mean number of observations per site: 12 Sites with at least one detection: 34 Tabulation of y observations: 0 1 485 103

49 sites Maximum number of observations per site: 12 Mean number of observations per site: 12 Sites with at least one detection: 6 Tabulation of y observations: 0 1 575 13

I am confused how the second species was only observed 13 total times, with 12 observations at a single site (maximum number of observations per site), and the mean for all sites is also 12 observations? I'm having a similar issue with the first example, as I don't understand why the mean and max are the same. However, when I look at examples of other code, this doesn't seem to be an uncommon situation. Is anyone able to help me understand if this is an issue with how I am interpreting results, or is there likely a bug in my code somewhere causing this?

Thank you!!

Lilo

[Ken Kellner]

Hi Lilo,

The max/mean observations in the summary refer to the number of repeated samples per site, not the number of times you observed an animal. It appears that at every site, you sampled 12 times (i.e., your y-matrix has 12 columns). If you had some missing values in the y-matrix, the mean would be lower.

I also find this wording confusing!

Ken

[Lilo Schultz]

Ah, that makes so much more sense! Thanks, Ken!