In this study 2 theories have been tested: Minimum Range theory (de Swaan, 1970; Leierson, 1970) and Minimal Resource theory (Caplow, 1956; Riker, 1962; Gamson, 1964). In an experimental simulation (Runkel and McGrath, 1972)political attitudes (left, centre and right) and power differences (40 seats in parliament, 30 seats and 20 seats) have been induced.
The results suggest that in the beginning of the bargaining process people communicate about the composition of the coalition programme. The minimal range theory may explain this behaviour: parties with more similar ideological interests do coalesce. Later on, one more often bargains about the division of the outcomes, i.e. portfolios. Minimum Resource theory only partly explains the formed coalitions. Minimal winning coalitions, which are predicted by Minimum Resource theory, are formed more often within centre-left-coalitions. This is not the case for centre-right-coalitions. It is discussed that the link between the parity norm and minimal winning coalitions, which is assumed by Minimum Resource theory, possiblv does not hold in this experiment. The parity norm being used by right together with centres strong position leads to the frequent occurrence of minimal winning centre-left-coalitions.