HypoTestInverter and 0 computed error

I am running cls limits with HypoTestInverter in 5.32.02. Often i get something like
computed upper limit is: 1.16974 +/- 0

a. is this result still valid in spite of the identically = 0 error? the
expected errors seen reasonable.

b. can one explain why this (identically = 0) occurs?

c. i’ve tried varying npoints and ntoys which sometimes results
in a more sensible error (or sometimes the dreaded ERROR, some proxies could not
be adjusted error), but no pairings that are consistent. is there advice how
to avoid this?



If you get the zero error is because you are using the asymptotic approximation. This error in the limit is obtained by propagating the statistics uncertainty in the p-value due to the limited number of toys (pseudo-experiments). In case of the asymptotic calculators, no toys are used, therefore there you have an error = 0.

In reality an error could be computed from the fact that the points are interpolated. I am planning to update the class to compute this.

Thank you for your post