1. A method for processing data in a computing apparatus from a test subject to signal a forewarning of a critical event, comprising: acquiring a plurality of sets of data received from at least one channel of data for sensing a condition of at least one test subject; computing a composite measure of dissimilarity (C i ) from normalized measures of dissimilarity (U) for distribution functions derived from a connected phase space and for distribution functions derived from an unconnected phase space for each respective channel of data; computing a cumulative sum of the composite measure of dissimilarity (Σ i C i ) over a series of time frames; applying a straight-line fit to the cumulative sum of composite measures (Σ i C i ) using a least squares calculation; computing a standard deviation (σ) between the straight-line fit and the cumulative sum (Σ i C i ); determining a forewarning threshold (U FW ) for detecting failure forewarnings, wherein said threshold corresponds to a minimum in said standard deviation (o); determining a failure value threshold (U FAIL ) corresponding to a value of the composite measure of dissimilarity (C i ) that signals an impending critical event; and providing a visual or audible forewarning signal of the impending critical event to a human observer after either one of 1) N FW successive occurrences of C i above the forewarning threshold (U FW ) or 2) after N FAIL successive occurrences of C i above the failure value threshold (U FAIL ).