Measuring a digital blood pressure monitor for better or worse, to look at any random error and systematic error of measurement results. Same time, same instrument measure blood pressure may be high or low is different from, it is called random error. Quality of the random error is reflecting the digital blood pressure monitor important basis for good equipment at continuous measurement of blood pressure difference will not be too large, if the results differ, describe the instrument of the random error is too large, and should not be purchased. Wu 旸 told reporters that in order to reduce random error, people at home blood pressure measurement can be measured more than once, write down the numerical average, the average will be our true blood pressure. In addition to random error, electronic blood pressure monitor system errors may also be present. System error is a sphygmomanometer to measure blood pressure than the exact value is higher or lower. Such as when someone's actual blood pressure 120/80mmHg, but using the instrument again measurement result is 125/85mmHg, indicating that there is this instrument 5mmHg of system errors. System error, the people at the time of purchase cannot be seen, can take blood to hospitals, and hospitals measured blood pressure values to see whether there are systematic errors.