The starting point column in the Page Critic tells you how far down the page a particular area begins. The Starting Point column is displayed only when you turn the detail lines on by de-checking the "Summarize" checkbox on the Page Critic screen. This number is in terms of the number of words down the page it starts at.

This statistic is useful in determining how prominent a heading tag, hyper link, or other area appears in relation to the top of the page. In general, the closer to the top of the page a keyword/area appears, the higher it will be scored.