When group decisions involve the allocation of resources to group members, the members might have an incentive to strategically distort any information they provide to increase their share of resources. The paper compares several simple multi-criteria group decision methods with respect to this problem. We show, using a computational model, that strategic manipulation of preference information is possible in all of the methods, although to a different extent. Furthermore, when the true solution generated by this methods is not Pareto-optimal, manipulation attempts might even improve the efficiency of outcomes.