: Variation in performances of an Information Retrieval system, which merges results from a number of retrieval schemes possessing equal and unequal weights, is studied in this paper. Weight of the retrieval schemes for a particular document is derived from the relevance scores of that corresponding document. Since, the relevance scores are varying from document to document and corpus to corpus, the method proposed is dynamic. A number of weight calculation methods, which are using the error value for computation purpose, are discussed in this paper. The effectiveness of the weight calculation is tested over three benchmark test collections viz., ADI, CISI and MED. It has been identified that the methods discussed in this paper retrieve articles effectively and they are independent of history or any training data.