Methods and systems are described for filtering out signal strength data associated with access points and a client device using heuristic and intra-access point analysis. The filtered data may be used to approximate the location of the client device. By filtering signal strength values through a heuristic and intra-access point analysis; the systems and methods described eliminate inaccurate or anomalistic values, which may negatively alter the estimated location of the client device. Accordingly, the systems and methods may produce more accurate client device location estimates by intelligently examining detected signal strength values.