Site's Traffic has Decreased

Hello, in this month of July i saw in google analytics that my traffic decrease everydays, and the only changes that i've done are:

update vBSEO version 3.2
update Sitemap Generator 2.2
archive completely removed:
35 URLs containing "/sitemap/" were viewed a total of 398 times

Pageviews 398 % of Site Total: 0.03%

what could be happened?

/sitemap/ is the Archive. it is NOT the vbseo sitemap.

kill it.
[How To] Completely Turn Off the vBulletin Archive
Why the vBulletin archive is useless and counterproductive

yes but i have Rewrited Archive Root to /sitemap/

Google Webmaster Tools - Recommended for All vBSEO Customers

Thanks Joe but i haven't big errors, just pages not founds because removed for spam.

having 404 warnings is ok, so long as the page in fact does not exist.

google displays it as a warning because they think it should be there. if you deleted it, it will no longer be there and should rightly 404

yes ok, but i don't know why the traffic has decreased, i've tried also to validate the page and there are no errors, Brian you have some suggestions for my community there are not great contents there are alot images, pictures, wallpapers posted by members etc. etc.

Thanks

A month ago i have used this changes,

"Force Forum Root as Homepage?" setted on yes

Define Homepage Aliases i have only added in the box: index.php

Could have this setting an impact in traffic?

Originally Posted by meonet

A month ago i have used this changes,

"Force Forum Root as Homepage?" setted on yes

Define Homepage Aliases i have only added in the box: index.php

Could have this setting an impact in traffic?

These changes should not have had a negative impact on your traffic.

Originally Posted by rensquared

How will I know if my website decreases traffic? What tools must I use?

Google Analytics is one good solution which a lot of webmasters use.

neither of those are remotely accurate.

analytics IS.

Originally Posted by rensquared

Why is that?? What does the analytics have that the two doesn't?

AW is basic server stats. Alexa isnt' really meant for analyzing traffic for webmasters, but more for outside sources. Analytics is very accurate and detailed.

However like the title say my traffic has decreases again in this days and i don't know why.

I hope to have some improvements after some changes that i've done recently.

Originally Posted by rensquared

Well, what does analytics have that make it very accurate and detailed?

Analytics is embedded in the site to track pageviews.

Alexa is toolbar based. Not everyone that visitors your site will have that. Therefore, Alexa bases its ranking on statistical estimates, not precise data.