Methods and devices configured for analyzing sensing vectors in an implantable cardiac stimulus system. In an illustrative example, a first sensing vector is analyzed to determine whether it is suitable, within given threshold conditions, for use in cardiac event detection and analysis. If so, the first sensing vector may be selected for detection and analysis. Otherwise, and in other examples, one or more additional sensing vectors are analyzed. A polynomial may be used during analysis to generate a metric indicating the suitability of the sensing vector for use in cardiac event detection and analysis. Additional illustrative examples include systems and devices adapted to perform at least these methods, including implantable medical devices, and/or programmers for implantable medical devices, and/or systems having both programmers and implantable medical devices that cooperatively analyze sensing vectors.