Panda? Google Penalties? SEO Traffic Drops? SEM Quality Score Drops? How you can find what happened:
In this article I will show you how to investigate a drop in your SEO Rank – and how to Investigate in General… I am often asked how I found the magic “answer” or the “Aha Moment” – the reason that traffic or keyword rank dropped for one or several companies. It is actually fairly easy and Google and Bing provide great tools to look through their eyes into your site.

SEO & SEM – Simplicity of Investigation:

 

Investigation boils down to this one thing: Keep asking yourself “What Don’t I Understand”. Once you answer the first question, you will find something else you don’t understand and you just “pull the string” all the way down until it all makes sense. And Its that simple. My friends and I at The Search Agency used the phrase: “Aha Moment”. At the bottom of the questions will usually be a large situation that makes the whole thing make sense. Like someone blocked all robots in the “robots.txt” file or an issue that makes all other issues clear.
Taiichi Ohno, considered to be the father of Toyota’s Production System, encouraged everyone in the company to always ask WHY about everything they did – especially when problems showed up. He believed that “having no problems is the biggest problem of all.” His famous statement was, “Ask ‘Why’ five times,” to get at the root cause of the problem.

SEO and SEM – How To Use Webmaster Tools For SEO

When it comes to improving websites SEO my motto is: Increase every statistic possible. But when an unexpected drop or increase occurs this is what I do:
Step 0: Create Google and Bing Webmaster Tools Accounts.
Step 1: Check Webmaster Tools to see exactly what Keyword Impressions decreased or increased.
Step 3: Keep asking yourself “What don’t I understand?”. Then I pull the string until I find that “Aha Moment”.
Step 4: Correct the error and ensure the traffic resumes.
Google Webmaster Tools is one of the tools that I really like and which can be very helpful to site owners and webmasters to figure out what problems their site has, fix potential errors, and provide Google some feedback on how our sites should be treated. For the most part, the information provided to webmasters through Webmaster Tools is stuff that Google already knows. They collect this data whenever they crawl your website. Webmaster Tools just provides a way for us to see your website through Google-tinted glasses.
Check out this great article by a Dutch Friend of mine over at Yoast – who explains details on how to use Google Webmaster Tools for SEO.
Google Webmaster Tools reports are now included as part of Google Analytics. You may recall several months ago,  Google Analytics launched a pilot program  between the two services. The  Analytics team announced  the initial test are over and everyone will now be able to link Webmaster tools and Google Analytics accounts. They’ve even enhanced the services based on feedback during the pilot.
Google Webmaster Tools and Bing Webmaster Tools – I call them “Google Goggles” and “Bing Binoculars”.
Google Webmaster Tools and Google Analytics are essentially a means for website owners to ensure that Google can easily find, crawl, index, and categorize their website appropriately. GWT provides website owners with detailed reports about their website’s search engine visibility, which can be leveraged to improve outcomes. After creating an account and verifying their site, site owners can log in to access these reports at any time and use these to see drops in impressions on any given keyword.