Measuring the impact of your investment in search engine optimization can be tricky. You can monitor rankings or traffic from search engines -- but that’s not enough. You need to uncover whether SEO has affected your bottom line.

We interviewed three search marketers to get their best advice on measuring SEO impact. Below are seven tactics pulled from interviews with:
o Chris Knoch, Principal Consultant, Best Practices Group, Omniture
o Herndon Hasty, Senior SEO Manager, Range Online Media
o Kerry Dean, SEO Account Manager, Range Online Media

A reliable, well-installed and well-managed analytics package is a vital first step to monitoring your SEO results. Your marketing team and the IT department should good buddies, and reports should easy to create and review.

Once you have the data, here are 7 ways to see if your efforts are having an impact:

Tactic #1. Separate branded from non-branded keywords

When someone searches for your product or company by name, you likely reached them previously through another marketing channel. Whether they saw it on television, heard it on the radio, or saw it in an online display ad, the searcher got your brand name from somewhere.

A good natural search strategy will ensure that those searching for your brand will find you easily. However, the return from SEO is more heavily based on the number people who find you while searching for general, relevant keywords.

To best judge the impact of your natural search strategy, separate your branded and non-branded keywords in your analysis. For example:

- If a teapot retailer named TeapotPlanet captured a sale from the keyword “red teapot” through organic search, then that sale should be attributed to SEO efforts.

- If the keyword was “red teapot TeapotPlanet,” then another marketing effort or a previous sale likely drove the search.

Tactic #2. Build calendars

You should be looking at your natural search data on a week-by-week or a month-by-month basis to uncover seasonal trends.

Also, match the data to a calendar of changes to your website, such as when you:
o Add significant content
o Reorganize content
o Change technology or architecture
o Employ SEO best practices

Matching your natural search traffic trends to your site changes will help uncover which changes are having the greatest impact. Changes to your website can take two to four weeks (give or take) to be indexed by the search engines. And it will take another few weeks for those changes to translate in traffic behavior.

Also, if certain keywords were involved in your changes, make sure that they’re on the calendar so that you can watch the performance of those terms specifically.

- Additional calendar for marketing campaigns:

You can also match the timing of your natural search data to other marketing campaigns. The campaigns will likely drive searches for your brand or product name. Watching your branded keyword performance immediately following a campaign’s launch can give you a fuller picture of the campaign’s impact.

Tactic #3. Tie keywords to KPIs

High rankings on search engine results pages and a good amount of traffic are important -- but they are not the ultimate goal of optimization. You want to uncover the impact of your efforts on the key revenue-driving metrics of your site.

“Rank is kind of going out the window, and even where you are on the search engine results page just because of Google’s Universal Search, as well as its Personalized Search program,” says Knoch.

Google’s Universal Search initiative adds images, news, maps, and other content to its standard Web search. Personalized Search creates customized results for each user. (See links below for more detailed descriptions.)

Traffic is not the ultimate arbiter of natural search success, either. You can attract a ton of traffic, but it might not be the right traffic. Or, you might not be properly monetizing the traffic. You have to drive the right traffic and be efficiently monetizing it to realize the full impact of your SEO efforts.

For example, an ecommerce site might measure SEO efforts using:
o Sales and revenue
o Average order value
o “Micro-conversions,” such as visitors checking product pages or adding products to a shopping cart

Tactic #4. Compare search metrics to your total site’s performance

A good way to know if your optimization strategies are paying off is to compare your natural search metrics to your overall site metrics, Hasty says.

For instance, if you see that your natural search revenue is up 15% year-over-year, and your site’s overall revenue is flat, that’s a good indication that your natural search program is doing well.

“If all of your organic search is growing, but not as fast as the rest of your business, then you’re doing something wrong,” and there’s room for improvement, Dean says.

Tactic #5. Don’t forget offline conversions

For marketers who generate sales leads through natural search, it is important that the leads’ performance is monitored and tracked on a keyword basis.

The number of leads generated by each keyword is easy to monitor. But it’s more difficult -- and more important -- to know the ultimate conversion rate of those keywords. You can only judge a keyword’s true performance by knowing its conversion rate.

An insurance company, for example, might drive natural search traffic to a landing page that has a form to fill out to request a quote. Once users fill out the form, they receive a quote and become leads for the sales team. If the sales team closes the sale over the phone or in person -- or doesn’t close the sale -- that information should be tied back to the original keyword. This will help you more accurately represent the performance of that keyword and of your overall natural search campaign.

Tactic #6. Drill down to diagnose problems

You want to avoid focusing on the details of individual keywords to the point that it blinds you to overall trends. However, if there are keywords that you think should be performing better, drill down to the metrics specifically associated with those keywords and their landing pages.

Break every step the visitor has to take into micro-conversions and look for bottle necks. For example, a product details landing page might have the following click-path:
o Visitor arrives at page
o Clicks to purchase
o Enters personal information
o Selects shipping
o Submits final review

Look for big drops in the percentage of visitors proceeding to the next step. A large drop off can signal problems with page, which might include design or relevance to the keyword.

Tactic #7. Monitor links

Monitoring the links that point to your website will not help you understand how much revenue your natural search strategy is generating. However, it will help you determine if you need to tweak your outreach strategy -- a vital portion of good SEO.

Disseminating press releases, reaching out to bloggers, and engaging online communities are effective ways to build in-bound links to your site, which can help boost your rankings and traffic. If you want to know how much these efforts are helping, start by seeing how many links they’re earning you.

Some analytics packages come equipped with link information. You can also use external tools provided by the search engines to help you measure. For example, Yahoo!’s Site Explorer (free and linked below) will list every link that Yahoo! has indexed as pointing to your site. In the options, be sure to select “except from this domain” to exclude internal links on your site, and select “entire site” to include links to every page on your site.

“Between all of them, Yahoo! is the most reliable for that type of information,” Hasty says.