I have successfully bound an XmlDocument to a DataGridView but all fields
seem to be strings. I want to retrofit appropriate datatypes on some of
the fields. Let me take this in 2 parts.

Part I:
I found the ValueType field, leading me to believe that I could say

dataGridView.Co lumns["mean"].ValueType = typeof(Double);
dataGridView.Co lumns["sum"].ValueType = typeof(Integer) ;...