Page Depth and Bounce rate are two very basic web analytics metrics. Page Depth is the average number of pages visited during a site visit. Bounce rate is defined as the percentage of users who land on a webpage and exit the website.
How actionable are these?
Not a whole lot.
Page depth would provide the avg. number of pages viewed in a visit – it could be the same page refreshed 10 times and show a page depth of 10. However, this page could not be providing any business value. A consumer who views 2 pages with very high business value would have only a page depth of 2. Thus, from a business point of view, the consumer who had a page depth of 2 is more valuable. Page Depth – Didn't provide the correct picture.
Now, let's talk about the bounce rate. A segment of consumers land on a web page, consumes the content, and exit the website, yielding a bounce rate of 100%. However, this webpage is able to provide all the information the consumers are looking for and leaving the website. Thus, if you look at the bounce rate metric, it doesn't provide the correct picture.
The better way to measure the effectiveness of your website, is assigning business value to various pages/activities of the website. Calculate an average value per consumer visit and improvise the website to increase the avg. business value per visit. Analyze the click-stream (pathing analysis) to help increase the business value per visit.