Introduction: This paper presents an initial proposal for a formal framework that, by studying the metric variables involved in information retrieval, can establish the sequence of events involved and how to perform it. Method: A systematic approach from the equations of Shannon and Weaver to establish the decidability of information retrieval systems and Conrad's equation is used to interweave the ecosystem components. Analysis: This work was developed from a detailed analysis of the scientific literature on information retrieval and through a set of inductive processes; it has been possible to build each of the components of this proposal. Results: First, we have proposed a simple way of assessing the implications of the sequence of events that occur in a search related to the overall response. Secondly, we obtain a formal equation that determines all the interrelated human and technological elements in the information retrieval processes. Conclusions: The establishment of this formal framework allows us to ascertain why we evaluate information retrieval and how one has to intervene in times of imbalance. (Contains 3 figures.)