Combine biased and unbiased samples

It appears on Statistical Science V21 N.4 2006 Nov. p517 biased sample: non-random sample/ convenient sample Graves et al (2006) developed a hypergeometric model with a bias parameter to identify the feature-prevalence in a population when convenient samples are used. MCMC was used and the prior on bias parameter was set as lognormal. Graves et al (2006) was on Technometrics.