The gap between your reading and your real pressure
A 2016 study published in the Journal of the American Heart Association found that nearly 70 percent of patients using home monitors were making at least one technique error significant enough to distort their readings. The errors were not rare or careless, they were the default. Most people sit down, strap on the cuff, and press the button without knowing that the number they get reflects as much about how they sat as what their arteries are actually doing.
