In the SHHS data set there are two heart rate variability values, sdnn and sdnnidx, that are a standard deviation and a mean of the standard deviations respectively. Which is/are the mean variable(s) they are referring to?
Thank you in advance for your help!
I have a question regarding the SHHS data set: where can I find the mean heart rate that has been measured during the first PSG? I found only a variable called Instantaneous Heart Rate, but I am not sure how it has been calculated – is it a mean? If yes, out of how many measurements?
Thank you in advance.