1. A method of selecting a default sensing vector for use with an implantable cardiac stimulus device system, the system comprising: an implantable medical device adapted to define a plurality of sensing vectors between electrodes implanted in a patient, and a programmer adapted for communication with the implantable medical device, the method comprising: the implantable medical device capturing cardiac signal data using at least one of the plurality of sensing vectors; (x) analyzing data related to the captured cardiac signal data to establish a set of detections separated by intervals, the set of detections including a first detection in time and a series of detections occurring after the first detection; (y) analyzing the set of detections by identifying the first detection in time as a QRS peak and, for the remaining detections performing the following until a predetermined number of QRS peaks are identified: comparing an interval from a preceding detection to a threshold and, if the threshold is exceeded, identifying a detection as a QRS peak; if not, comparing the interval from the preceding detection to a prior interval and (i) if the interval and the prior interval are similar within a boundary condition, advancing to amplitude analysis; if the prior interval is shorter outside the boundary condition, identifying a detection as a QRS peak; or, if the prior interval is longer outside the boundary condition, identifying a detection as a Noise Peak; and if consecutive detections are identified as QRS peaks, identifying a Noise peak therebetween; if the step of comparing the intervals leads to amplitude analysis, performing the amplitude analysis by comparing the amplitudes of two detections to one another and binning the latter detection of the two detections according to whether it is approximately equal to, within predetermined bounds, larger than, or smaller than the earlier detection of the two detections; and if all of the detections have been analyzed in the comparing the interval step and less than a predetermined number of QRS peaks have been identified, determining whether a threshold number of detections are in the approximately equal to bin and, if so, declaring a bad vector; otherwise, further parsing the detections by amplitude into QRS peaks and noise peaks and calculating a vector score using each of the average amplitudes of identified QRS peaks and Noise peaks in a polynomial formula; (z) if a score is generated in step (y), comparing the score to a threshold and, (i) if the threshold is at least met, determining that an identified sensing vector is suitable for cardiac event detection; or (ii) if the threshold is not met, or if a bad vector is declared, determining that one or more other sensing vectors is to be analyzed.