Dashed line: Sreekumar et al. (1998) determination of the EGRB. Solid line: Strong et al. (2004a) determination of the EGRB (best guess). Dotted lines: Strong et al. (2004a) determination of the EGRB (systematics‐based limits). Thick solid line: Collective spectrum shape of unresolved unidentified sources using maximum likelihood intrinsic spectral index distribution (ISID) parameters for sample 1 (this work). The amplitude of the spectrum does not constitute a prediction; rather, it has been maximized so that it does not exceed the observed EGRB in any energy bin above 100 MeV. Thick gray lines: 1 σ uncertainty in the spectral shape of unresolved unidentified source emission for sample 1, entering through the statistical uncertainty in the ISID parameters.