On what basis do I select frame size and mul factor in Z-score analysis?Is it just a random guessing?
If we increase the frame size the shape of the thresholding line starts changing also the starting point of the thresholding line starts moving ahead. And if you increase the value of mul factor or C the threshold line moves further away from the standard data points, likewise if you decrease the threshold line moves closer to the standard data points . Depending on these you can set the values for frame size and mul factor. I am guessing this answers your query.
Since Threshold line(Tn) and Multiplication factor © are proportional. If we increase C distance between threshold lines increases. And if you increase the value of c distance between two threshold line decreasea as it move towards the standard line. According to this you can set the Value of C (multiplication factor)