Planning Poker in cost estimation in Agile methods: Averaging Vs. Consensus

Software cost estimation has been always a serious concern among the software experts. Although, a few estimation models and techniques have been provided in disciplined based software methodologies, Agile methodologies most often use Planning Poker technique for software cost estimation. This technique promotes coming to consensus when suggesting size of each user requirement (known as User Story). However, most often software experts ask whether it is necessary to reach to a consensus or not. They also, offer considering the average of the suggested sizes (cost) of User Stories instead of focusing on consensus on them. The main aim of this paper is to present the results of a case study research which has been carried out to compare the accuracy of both disciplines. The results show less accuracy when team get an average size of the User Stories compared to coming to consensus about the size of User Stories.