Ignacio Zact was a fifteenth century mathematician consumed with the notion of describing physical phenomena in measurements that were as precise as possible. (Indeed the root of the English word "exact" is derived from his name.) However, although his measurements were "exact," they were just as often inaccurate. For instance Zact measured the shortest distance across the English Channel (between South Foreland and Cap Gris Nez) to be 41.955473711 km at mean high tide, a precise measurement to be sure. However the actual distance is closer to 34 km.
Nevertheless Iggy, as he was known to his friends, insisted that measurements, whether they be of space, time or mass, be ever more acute. Late in his life he would become enraged at those who casually referred to measurements as "approximately" or "about" or especially "more-or-less."
Those with Zact's Malady are known for being precise without being accurate. In conversation, they are easily disturbed by information cited that is not precise and detailed—even if that information is incorrect.
Related to Correctanoia, Zact's Malady is a difficult microdisorder to diagnosis because it requires in-depth knowledge of subject matter that is usually better known by the patient than the diagnostician.
The treatment of Zact's Malady has been difficult until recently. Now, a company called RoundOff has developed a smartphone application that teaches people how to approximate precise values. For example, with a user's phone activated and the application running, a loud auditory signal is delivered when a string of numbers is detected, reminding the user that an acceptable limit of precision has been reached. Depending on the patient's stage of recovery, the signal can be adjusted to the number of digits detected in a string.
Click here to review a case study of Zact’s Malady.