Keyword selection is the most important aspect of SEO strategy. If you target the wrong keywords, you could be wasting time and money on a strategy that will never deliver the goods.

SEO keyword selection is part art, and part science. It’s an art in that you need to think like your audience, and evaluate each keyword’s relevance as it relates to your brand and objectives. It’s a science in that once you’ve compiled a list of potential keywords, it’s a numbers game. Ultimately, you’re looking to strike a balance among Monthly Search Volume, Level of Competition, and Keyword Relevance. All three factors must be optimized if you want to maximize ROI on your SEO strategy. But how do you put it all together to evaluate which keywords are right for your site? I’ve created metric called the Keyword Optimization Index to help evaluate keywords. Here’s how it works…

Monthly Search Volume

Keywords with high search volume have a greater potential for success. The monthly search volume can be found using the Adwords Keyword Tool. Enter the desired keyword(s) into the text box, and the Local Monthly Search Volume is returned, along with other suggested keywords (which you can consider using as well). One caveat in using this tool is that if you’re using the Local Monthly Search Volume, you must select the appropriate country. By default, USA is selected, regardless of your location. If that’s the market you’re targeting, leave it. If you’re looking for a specific country, make sure you use the appropriate selection. And if you want the global volume, use the Global Monthly Search Volume column. This distinction is important, because search patterns change from country to country.

Level of Competition

Keywords with low levels of competition have a greater potential for success. Level of Competition is literally the number of search results for that keyword. Go to Google, and search for the keyword you’re evaluating, and record the number of results returned.

Keyword Relevance

The final factor in keyword selection is keyword relevance. The more relevant a keyword is to your brand and objectives, the higher the potential for success with that keyword. As a general rule, keywords should be more than one word long, unless that one word is extremely relevant, and you have a large budget for SEO. Being more specific with your keywords generally improves relevance. But beware the pitfall of going too specific, targeting keywords that have very low search volumes (fewer than 200 searches per month). On a scale from 1 to 10, give each keyword a score for relevance as it relates to your brand and objectives.

To provide an example, if your company is a store selling children’s books, “children’s books” is a more relevant keyword than “books” and as such, it should have a higher relevance score. Once you have compiled your list of potential keywords, give your most relevant keyword a 10, and your least relevant a 1. Give each other keyword a score based on the range you’ve established. Note, this is the most challenging, and important part of keyword selection (the “art” part). Do not move too quickly on this step, and it would be good to discuss this with the person in your company who is most in touch with the brand.

Keyword Optimization Index: Putting it all Together

Ok, so we now have a list of keywords, search volumes, level of competition, and relevance scores. How do you combine everything? I’ve done some research on mathematical formulas which combine all three of these factors (volume, competition, and relevance), and strangely I couldn’t find anything (at least that’s publicly available), so I decided to have a go at it myself. The result is an algorithm that I feel that is very useful: the Keyword Optimization Index.

The higher the K.O.I., the higher your ROI. I’ve tested it out with various scenarios, and it’s stood up to every challenge I’ve thrown its way. K.O.I. increases exponentially, as the relevance score increases (that’s where the “log” comes into play). A relevance score of 1 almost always returns a very low K.O.I. unless competition is extremely low, and volume is extremely high (rarely the case). A relevance score of 10 has a good chance of a high K.O.I. unless competition is disproportionately high compared to volume. So, just to emphasize the point above, assigning the relevance scores must not be taken lightly.

Once you’ve calculated the Keyword Optimization index for all keywords in your list, you can decide which keywords deserve your focus. There is no target value you’re trying to meet for K.O.I. — you just want it to be as high as possible. So you don’t spread yourself too thin, focus your efforts on a short list of keywords (around 15-30, or more if you have a big budget). Eliminate the lowest scoring keywords until you have a set until you have 15-30 keywords with high K.O.I.’s. Congratulations, you’re well on your way to a successful SEO strategy!

K.O.I. Calculator

I’ve created an Excel spreadsheet to help you calculate the K.O.I. for your keywords. Input your Search Volume, Monthly Search Volume, and Relevance Scores, and the K.O.I. will be calculated. If search volume is under 200, a K.O.I. of 0 will be returned. This is because a volume of 200 searches per month is not worth your time.

Download the Keyword Optimization Index Calculator

I’d be interested to hear feedback on this algorithm. If there are any ways to improve it, please let me know. Did you use it? How were the results? Let me know!