I think, your charting task can be accomplished without resorting to VBA. Check out the dynamic charting web site of Tushar Mehta and the links provided therein. There are various charting examples available and you should find a model for your task.

www.tushar-mehta.com/.../index.html

Hope this infomation is of some use to you.

Defining a start and end of the range dynamically  is fine but I want
to be able to selectively exclude some points  (outliers) from the
middle so that they are not plotted in the chart  and not considered
in the trendline or estimation of the correlation coefficient.

Can you please help?

Charting with VBA in an advanced subject and one that even some of the top
MVPs hate to tackle. With that in mind, here are comments from Excel MVP and
Charting guru, Jon Peltier when I asked him about a similar question some
months ago. Take his advise for what it's work. And you might want to also
check some of his charting articles, particularly his FAQ in TechTrax. His
article link is also below...