The following image shows the importance of sampling rate and vertical resolution. Ecg and pressure waves were simultaneously captured in the same patient with PulsePen (lower window) and a much more expensive, well-known and popular, tonometer (upper window). After examination, data were exported in ASCII format and compared to each other: it is very clear the difference in terms of the horizontal number of points (samples/sec) and vertical resolution (LSB = least significant bit).
The points correspond to the captured samples while joining lines were added between points to facilitate the graphical "reconstruction" in the upper image: