Why Does Bounce Rate Matter and How Does Google Measure a Bounce?

i don't understand your question. if you want to get the answer of both questions then clearify and if not then which is your question in these two

Is Web Directory Submission Still Good for SEO?
Why Does Bounce Rate Matter and How Does Google Measure a Bounce?

1, no : Google webmaster tools, Bing Webmaster tools, nothing else

2, the number of visitors : who leave after 1 page view ∴ implying something is wrong with design or content
( or they got what they needed on the first page )

3, count single page sessions : not an accurate measure if the site is well designed, well SEIndexed,

information contained on a single page,
linked by search engines,
will show as a bounce, when it was a success

if u have high bounce rate (people leaving your website as soon as they arrive without visiting other pages)

this means u wont get leads (business)
this means u wont get sales

so if ur bounce rate is high u need to invest in some usabilility/user experience design & also ensure u have the right content

I will answer for the first question "is web directory submission still good for seo?" Only high quality directories are helpful for the seo. These high quality websites can be found only a few. Previously this technique was very effective but due to the various google updates, its not very helpful nowadays.

Its good but does not have much importance. Try submitting your website in web directories having PR5 and above.

Simply to say - NO. It is helpful onlay at initial statge to garner some quick links and to establish website's presence in online world. I would not make it regualr excercise of seo plan.

No, i don't think so directory submission is still efective. In these days forum posting or social bookmarking is working but condition is that content is must b original or good quality.