Question

) If the regresion is our measure of the center (the central tendency among a set of x,y data value pairs), what is the measure of spread and how is that calculated?

Answer 1

Variance or standard deviation is used to calculate measure of spread.

Suppose, corresponding random variable be X. Also, sample size be n.

Then sample mean is given by

Then sample standard deviation is given by

If population mean is known then standard deviation is given by

Also, variance is squared value of standard deviation.