support of binomial distribution $Binomial(N, p)$is {0,1,…, N}.

In SBC, whose rank statistics are obtained by adding the number of smaller posterior samples out of L samples, the probability of a rank corresponding to 0 to L +1 being place outside of CI = qbinom(c(0.005,0.5,0.995), size= N, prob = 1/(L + 1)) is 0.01. On average, the counts in only one bin a hundred will deviate outside this band.