Suppose we have a population of size $N$ where each individual is represented by a vector of the form,
$v_i=(\lambda_1^{(i)},...,\lambda_s^{(i)})$
where $\lambda_k^{(i)}$ are finite discrete variables. We wish to estimate the probability of individual $i$ possessing a particular trait based on the values of $\lambda_k^{(i)}$. Suppose that the population has several unique clusters and that certain clusters are difficult to sample (i.e. in any given sample, the number of individuals representing that cluster is small). What are some methods to homogenize the samples to estimate the distribution of the trait?