A method carried out by a system configured to analyze blood. The method includes causing a ferromagnetic object to move in a chamber housing blood after clot initiation has been implicated. Movement of the object in the chamber is detected. The detected movement of the object is correlated with clot retraction of the blood. In some embodiments, the stop of detecting movement includes allowing the object to drop from a raised position and detecting a drop distance of the object. In related embodiments, the step of correlating detected movement with clot retraction includes reviewing a trace generated by a plurality of drop distances over time. In yet other embodiments, methods of the present disclosure can further including evaluating platelet function of the blood based upon assessed clot retraction.