I have some data (a set of numbers) and I want to compare them with the normal distribution using QQ-plot. The only statistical tool that I am aware of is Octave but Octave doesn't draw the reference line.
As can be seen in the above picture the x-axis has a range from - 3 to 3 but the y-axis has a range from 20 to 140. I think drawing a 45 degree slope line would be wrong.
How can I draw such a reference line in Octave? Or does there exist any easy tool that would draw a QQ-plot with that reference line?