Dilution Index Formula

The formula

The SEO Dilution Index, or SEO-DI, is a formula that represents the average number of pages competing for a specific search term. If you have this number before starting your SEO strategy, you are already ahead the competition.


D.I. = (Number of searches * 100) / Number of results

How to calculate

The first steps are a normal keyword researching technique. After you've got all the data, do the math and fine tune your marketing strategy.

Choose the keywords you are interested in;
Get a list of related keywords (search terms people type when searching for the keyword you have chosen);
Get the number of searches per month for each related keyword;
Get the number of results, given by Google - for this keyword, per month for each related keyword;
Calculate the formula;
Analyse.

1. Choosing keywords

Run a simple word density test on your page and focus on the phrases with 2 or 3 words
Run the same test against one or two of your high-ranked competitors an compare the results. If you think your wording can improve, write it again or hire a copywriter to improve the language in a way that doesn't affect the human readability
Select 2 or 3 keyphrases that you think fits best to your page

2. Listing related keywords and keyphrases

When you search on Google, you can switch on the feature that gives you suggestions of other phrases you might be interested in. That is a great clue to what you should go from there.
Alternatively you can use paid services that gives you hundreds of related phrases. Sometimes this is a good idea because if you run too many searches, Google will block you for a while. Not cool, believe me.

3. Getting the number of searches made per month

If you have an AdWords account, you can find this data in there. Seek for 'search volume', or something like that, an you will get the best numbers the Internet can give up.
Again you can use paid services for that.

4. Getting the number of results/competitors

Google will provide the best data: do a search and copy the number of available results at the top of the page, close to the search box.
Here is also a good idea to use third-part services so Google don't think you are a spammer.

5. Calculating the dilution index

Place all keywords and phrases with the numbers you've just got into a spreadseet
For each keyword/keyphrase (one per row) run the formula =((column with number of searches * 100) / column with number of results )

6. SEO Analysis

List all keywords with descendent order of SEO-DI (from higher to lower);
To select the best keywords for your SEO project, you should ignore the ones with SEO-DI bellow 0.01 (unless you don't have many options above 1.00) and ignore the ones with average volume of searches bellow 300 per month (the best keywords are the ones that people search on.. :) Less than 10 per day won't represent good business!);
Delete keywords you don't think is worth investing on, even if they have the best dilutions. Because your page should be written to humans, not to robots, delete the words that don't make sense on your marketing strategy.
- To be sure you are doing the right thing, answer these two questions: 1) Can I do business with people searching this term? and 2) Can I afford to spend my time, and resources, writing articles about this search term?
The best dilution is the one that fits in your SEO plan!
You should end up with a nice, juicy, list of terms waiting to become more competitive.
Whoever gets there first, gets higher!

Example

SEO project

Keywords selection plan: To find the best 5 terms that represent the search phrase "cms php" (which means I want to know about Content Management Systems developer in PHP), for my new free and simple CMS system, targeting a generic PHP developers comunity.

11 Best diluted keywords related with “cms php”:

Keyword	Number of Results	Average vol.	Dilution
jojo	26,800,000	823,000	3.07
modx cms	336,000	8,100	2.41
drupaled	33,500	590	1.76
modex cms	8,240	46	0.56
articlelive template	14,900	58	0.39
articlelive nx	36,700	140	0.38
expressionengine	1,160,000	3,600	0.31
articlelive	309,000	720	0.23
drupal	27,700,000	60,500	0.22
copyright 2002 by php nuke	576,000	1,000	0.17
drupal org	4,740,000	5,400	0.11
drupal 5.1	377,000	320	0.08
cms	134,000,000	110,000	0.08
c m s	134,000,000	110,000	0.08
drupal websites	709,000	480	0.07
opencms	2,600,000	1,300	0.05
dasboard	824,000	390	0.05
phpfusion	10,100,000	4,400	0.04
open source cms	8,720,000	3,600	0.04
portal demo download	1,630,000	590	0.04
opensourcecms com	1,000,000	320	0.03
powered by php fusion	4,450,000	1,000	0.02
content management system	122,000,000	27,100	0.02
simple cms	4,550,000	880	0.02

Data source: SEMRush.com

First Analysis

This list I can identify that most of whom search for "cms php" want to get information about specific CMS tool: Jojo, Drupal, Modx CMS, Expressionengine, Articlelive are all fantastic systems and people want to know more about them.

Now I can

Make articles tearching people how to migrate from these softwares to mine; and vice and versa.
Promote my addons by makeing them available to use with these other CMS systems.
Or I could just ignore them and try build my way up ranking targeting only the keywords that aren't related to competitors.

What would I do then?

From the list above, I would delete 'modex cms', 'articlelive template' and 'articlelive nx' for low average volume.
Because its dubious meaning, I would ignore: 'cms' and 'c m s'
Because the competition is tremendous (with PR of 7, 8 and 9), I would ignore: 'open source cms' and 'content management system'
Now we only have competitors remaining, and although it will be hard to rank higher than drupal.org for searching 'drupal', we will still be among lower competition and better dilution and other generic terms. So that's what we should go for.
I would focus on: 'jojo cms', 'modx cms', 'drupal cms', 'articlelive cms' and 'cms php'. Yes, 'cms php' must get in the list!

Now we have our first list ready

Keywords chosen:

Keywords and phrases selected

jojo cms

modx cms

drupal cms

articlelive cms

cms php

Summary and disclaimer

SEO-DIF gives us on instant view of which keyphrases are more liable for high ranking.
We can analyse with a more scientific vision.
If we want to go up Google's index you need to quickly write articles about these products (even if they are about the competitors - be careful with legal issues, that is your responsibility!) and than you can restructure your pages to intercept visitors from other sites by giving them what they want under your domain.