Segmented Regression Sample Size

#1
Hello,

I am using Segmented Regression (SegReg*) to compare proportional occurrence (Y) of 18 species vs. proportional habitat cover (X) to determine if abrupt changes occur in the relationship. Sample size N = 98 but only one species occurred in all 98. The other 17 ranged from 40-97.

Do I included or exclude zero's in the other 17 in the analysis?

thanks,

sherwood

*http://www.waterlog.info/segreg.htm