Question 6: Each participant completed three blood pressure measurements. The investigators calculated the mean blood pressure using the last two out of three measurements. By using the mean in analyses, the investigators reduced the influence of random error of the measurements and random variation of blood pressure that may occur throughout the day.

Imagine that the blood pressure cuff that was used by study staff was mis-calibrated so that the systolic blood pressure measurements were mismeasured. The study staff determine that each blood pressure measurement was 9 mmHg higher than the truth. The investigators discovered this error after the data were collected. They are unsure how this could impact their results so they consult you to help.

Based on the current available information, would you suspect that the misclassification of high ( 126 mmHg) vs. low ( 126 mmHg) systematic blood pressure is differential or non-differential with respect to the outcome?