Hi there,

I am working on diet analyses from scats and my situation is somewhat similar to the Karanth and Sunquist paper on prey selectivity in tigers, leopards and dholes (1995) in that I have scat frequencies as measure of resource use and intend to calculate the expected proportion of field collectable scats per prey species under the null hypothesis of no selectivity for comparison. I saw that SCATMAN does all the necessary selection statistics on these data, but have some questions:

1. Is there a reason why SCATMAN uses the Chi² statistic instead of the log-likelihood statistic advocated by Manly (2002)? My data fulfill two of the characteristics Manly names as causing different results between Chi² an the log-likelihood (small expected frequencies - 1 of 4 below five - and considerbale differences between observed and expected frequencies), so I wonder whether that could pose a problem.

2. Is there an available R code for the procedures implemented in SCATMAN (I always find that helpful to fully understand what's happening)?

3. As I have a small sample size (33 scats) with an uneven distribution of frequencies across four prey categories, three of my observed and one of my expected frequencies are below 5. Can anyone tell me whether in this case the bootstrapping implemented in SCATMAN is a reasonable approach to evaluate results, or whether it would make sense and be possible to re-do the analyses with a Fisher's exact test?

Thanks so much to all of you already; I hope I don't repeat what has already been asked, but I couldn't find a single SCATMAN related entry in this forum.

cheers,

Rahel