Methods, systems, and devices for signal analysis in an implantable cardiac device such as an implantable cardioverter defibrillator. In illustrative examples, captured data including detected events is analyzed to identify likely overdetection of cardiac events. Analysis of the apparent width of detected events is used to determine whether overdetection is occurring. If overdetection is identified, data may be modified to correct for overdetection, to reduce the impact of overdetection, or to ignore overdetected data.
