We find overwhelming odds against the hypothesis that all Type Ia supernovae produce gamma-ray bursts, whether at low redshift (:1) or high-redshift (:1). We also find large odds (:1) against the hypothesis that a fraction of Type Ia supernovae produce observable gamma-ray bursts.

We find very large odds (:1) against the hypothesis that all Type Ib, Ib/c, and Ic supernovae produce observable gamma-ray bursts. We also find moderate odds (:1) against the hypothesis that a fraction of Type Ib-Ic supernovae produce observable bursts. If we nevertheless assume that this hypothesis is correct, we find that the fraction of Type Ib, Ib/c and Ic SNe that produce observable GRBs must be less than 0.17, 0.42, and 0.70 with 68%, 95%, and 99.6% probability, respectively. These limits are relatively weak because of the modest size (20 events) of our sample of Type Ib-Ic SNe.

Copyright The European Southern Observatory (ESO)