The paper introduces a simulation, which was developed by Michael Krassa to model the opinion contagion. Krassa developed his model by using the theory of the spiral of silence that says that the perception of the public opinion influences the opinion assertion of the people and the threshold models that show how much support one person needs for the public assertion of his opinion. With the help of these relationships Krassa integrated the social networks in his model. We applied Krassa's mathematical model to two cases, the parliamentary elections of 2002 and the EU-parliamentary elections of 2004 in Hungary. We used hypothetical thresholds to examine the data because the actual threshold values are not known. The results of the simulation show that it can happen that we measure the minority opinion to be higher than the real distribution of the opinions as a consequence of the different distribution of the threshold values of the opinion assertion. This can be one explanation of the wrong electoral forecast. The problem is that the model helps little to give a better forecast because we have no data about the threshold values and we do not know the point where the dynamics of the opinion contagion stands at the time of the survey.