  The distributions of spectral characteristics and their correlations with
fluence, peak flux, or duration, are essential in understanding the nature of
GRBs. However, the selection effects involved in detecting GRBs can distort
these distributions. Here, we discuss how to deal with selection effects
involving the peak energy E_p of the GRB nu F_nu spectrum, which suffers from
both an upper and lower threshold. We describe a new method to account for this
double-sided truncation, and show that the true distribution of E_p is
significantly different from the observed distribution.
