It is becoming harder and harder to obtain the keyword data from both organic search and paid search. Keyword tool data has become unreliable. It feels as if we’ve entered the dark age of search engine marketing. The good news is that we still have 100% access to our own on-site search data! It is strange how not many companies are using it as one of the data resource. On-site search data is very much underrated in my opinion. It gives you the actual user data on your site instead of general data that are oftentimes standardized or averaged. The signals you get from on-site search data are far more valuable than stats and trends you read from other sites or businesses since it reflects actual user wants and needs as well as navigation and content gaps.
Here’s a list of valuable data that you can get from the on-site search, and how you should utilize them to improve on-site search experiences and your search marketing.

Search Queries
Considering the fact that the majority of site visitors on most websites come from the search engines and land on a specific page, we’d expect to see more long-tail search queries happening with on-site search. The most common being product numbers and spec (size, color, price range, etc.) related queries. You may also see some customer-support related queries. These support queries can often be an early warning sign to new bugs or problems with your product.
First, you want to check to see what search results come back for some of the popular search queries to ensure that you are providing the best list of content available on the site. Then, generate a report monthly to see which words are being searched and not producing any results or results that are not being clicked. Both these reports will help improve performance as well as identify content problems.
Many queries could be great candidates for the PPC campaign keywords. If you keep seeing certain queries showing up again and again, consider adding them to the SEO target keyword list, selecting a preferred landing page (PLP) for them, and optimizing them for the keywords.

On-Site Ranking Results
One of the goals for investing in SEO is to bring people to the best possible landing page that provides the information the searchers are looking for from the search results. This increases visitor retention and decreases bounce rates. The same idea applies to on-site search. Have you checked to see if your SEO PLP ranks for each SEO target keyword in your own on-site search results? A lot of work goes into PLP identification and optimization so why not maximize it? Unlike the external search engines such as Google and Bing, you realize that you have control over the on-site search results. Using “Top Page Biasing” function in most applications, you can actually specify which page should rank No. 1 for certain search queries. I suggest to all website owners to adjust their on-site search results by setting all of the key SEO words and their PLPs as the preferred page for the same phrase on on-site search. You can also remove the pages that you don’t want to show up in the search results.

Missing Content
On-site search queries tell the story about the site user behavior and the goals of their visits to the site. If you see one visitor using on-site search within a short period of time entering similar queries, it probably means that the search results weren’t providing what she was looking for. If you see the same queries used again and again by multiple visitors, you may want to add that to the taxonomy and in the navigation menu to help them find the page easily.
This user behavior may also be caused by the fact that you don’t have quality and relevant content for that topic on site. Review the list of related on-site search queries to identify the information they are looking for, and add that content to the site. Depending on the content, it may not be suitable for the company website. In that case, use blogs, forums, and other social media to create related content.

User Feedback
User feedback provides valuable information for improving the on-site search experience and overall site experience. You should always keep it to two to three short questions, and ask very specific questions to obtain the exact types of feedback that you hope to collect. The examples of questions related to on-site search would be:
1.    What search query did you use on-site search?
2.    What information did you hope to find with that query?
3.    Did you find the information in the search results?
The feedback should be reviewed to improve:
•    SEO and PPC keywords
•    On-site search results
•    Missing content
•    Site navigation and webpage wireframe

I believe that on-site search data would become one of the strongest weapons for the site owners to stay relative to the visitor and their customer base. I suggest you review the list of search queries periodically.

(Updated the original post on ClickZ Asia in 2012.)