In stratified sampling there are designs with one unit selected per stratum or when one is willing to make estimations on unplanned domains with one unit in some strata. In these cases the variance is generally estimated by the collapsed strata method, which requires identification of the strata...

We study the problem of information sharing in oligopoly, when sharing decisions are taken before the realization of private signals. Using the general model developed by Raith (1996), we show that if firms are allowed to make bilateral exclusive sharing agreements, then some degree of...