If you have implemented an SEO strategy your company has some sort of investment, whether it's time or money. Because of that investment, it's likely that someone at the company wants to know whether or not the investment was good or not. If you are in charge of marketing, you are the one to answer that question.
The tough part is, if you were to dive into a bunch of website analytics that attempt to prove the success of SEO, you will probably put your boss to sleep before you are able to show success. When it comes down to it, they don't care about pages per visit or bounce rate.
What your boss wants to know is how is the SEO strategy impacting their bottom line! So if you can't spit out a bunch of Google Analytics metrics, how do you report search engine optimization success?
Benchmark Your SEO Performance
This is the most basic way to show success. Even if your boss doesn't want to hear you spew out a bunch of data, they will likely listen to high level numbers showing change. The ones they'll probably want to hear about are traffic and conversions. Pretty easy to benchmark and show change.
They might want to talk about where you rank, which is tough because search results are so personalized. The best place to get this data is from Google Webmaster Tools where you can see your rank and change over time. This data isn't stored forever, so if you are looking for long term benchmarking be sure to capture data frequently.
That will provide them with basic, high-level metrics, but...that still doesn't show how SEO actually impacts the business.
Improve Conversion Tracking
If you want to report metrics your boss actually cares about, this is not an option.
Obviously to improve conversion tracking YOU MUST BE GENERATING CONVERSIONS. SEO should be part of a more comprehensive inbound marketing strategy which utilizes content marketing to generate those conversions.
If you want to provide the biggest impact with your reporting metrics you should be able track everything from visit through the close of a sale. Even if you cannot track through the close of a sale, you should be able to report something, X number of visitors, conversion rate, X number of unqualified leads, and X number of qualified leads handed off to sales.
These are the types of numbers your boss actually wants to see.
The topic of this was how to report SEO success, sure...but inflating numbers to show false success doesn't do anyone any favors. If your SEO experienced declines but you can show why and where those declines occurred, you can focus your efforts to improving them. This in itself is a success over traditional marketing.
The bottom line is you must report how SEO impacts what matters most to your business, show change over time and show factual numbers that can be used towards continued improvement. That's how you report SEO sucess to your boss!