Analysis of point transect data

Analysis of point transect data

Having mastered analysis of line transect data, we move on to analysis of point transect data. These data are more difficult to model because the region of the curve where we wish to be most precise is the region where data are most scarce.

Assessing fit to point transect data also represents a challenge. Consequently, we use plots of the probability density function to gain perspective regarding the influence of regions of the probability density function upon lack of fit.

Two data sets are to be analysed: the first is a simulated data set in which both the true shape of the detection function as well as true animal density is known. Fit various detection functions to these data, also examining the effect of truncation (truncation for points is often more severe than for lines) upon estimates. Look for congruence in density estimates–as you did with a similar exercise performed on simulated line transect data in Practical 3.

Finally, there are two optional data sets of winter wrens collected by Prof. Buckland. Same species and study area, but two different field protocols: one protocol used traditional 5-minute counts while the other protocol employed the “snapshot” method.

Lecture materials

Lecture discussion

Slides

Video

Exercise materials

Using R package

Video introduction

Instructions

Solution and discussion

Video summary

Using Distance for Windows

Video introduction

Instructions

Solution and discussion

Video summary

Supplemental materials

No supplements

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References