To reduce the subjectivity, the MIT researchers used a digital pen tool to monitor the patients’ drawings. The researchers used data from 2,600 tests done over the past nine years, monitoring dozens of other measurements that the pencil-and-paper test ignored. The digital pen, which is currently available on the market, can pick up thousands of little elements of the patient’s drawing, like how many strokes the patient took to draw the clock, how much time he spent thinking before drawing, or whether the numbers are drawn with little hooks on the ends. They used the data to create a model that can assess whether the patient showed early signs of cognitive impairment. When they compared their results to those of typical clinical tests, the researchers found their model to be significantly more accurate.