On-Page Difficulty is a measure of various factors that contribute to difficulty in ranking for the keyword based on the page's content. The lower the better the opportunity to rank.
Here is how this is calculated:
For each keyword, we get the top 10 Google search results and analyze them to figure out how well the top 10 results have done their OnPage SEO. If the On-Page SEO is not optimal, there is an opportunity to rank for this keyword.
For each search result in the top 10 we look at the following factors and assign it a weightage :
Does the website have the keyword in the page title (30)?
Is the keyword present in the URL (25)?
Do the headings like h1, h2, h3 etc contain the keyword (20)?
How about the description meta tag (15) and the content (10)?
The number in brackets is the weight given to each element - so, for example, it is more important to have the keyword in the page title (30) and not as important to have the keyword in the content of the page (5).
Every search result in the top 10 is given individual points and we then add up the points for all 10 results. This final number represents the On-Page Difficulty of the keyword. This number is then scaled down to fit in the 0 to 100 range. A higher number means that all 10 results are highly optimized.
Off-Page Difficulty is a backlinks based measure that demonstrates the difficulty in ranking for a keyword. The lower the measure, the better the opportunity to rank.
For each keyword, we get the top 10 Google results and analyze various metrics to figure out the quality of their backlink profile.
We use a combination of the different Moz metrics to get to a number between 0 and 100. This number determines the quality of the backlink profile for all the top 10 results. The higher the number, the better the backlink profile of the results and therefore the tougher it is to out-rank them by getting better links.
At present we use only Moz metrics but plan on adding Majestic and Ahrefs in the future.
The measure of overall SEO Difficulty for the keyword, which is a combination of On-Page and Off-Page difficulty. The lower the measure, the better the opportunity to rank.
To rank your website for any keyword, you need to do better On-Page and Off-Page SEO than the top 10 results.
SEO Difficulty = (65% of OffPage Difficulty) + (35% of OnPage Difficulty)
We conducted a bunch of tests and found that 65% of the weightage should be given to backlinks while 35% should be given to OnPage factors to get the best measure of SEO difficulty.
The Click Through Rate Scope metric is a measure of how much traffic you can expect to get. The higher the better.
CTR Scope represents how much traffic the top organic search result can expect to get. Some keywords are very competitive and you can often see non-organic listings shown above the organic listings - e.g. Google AdWord ads, Local listings, Snippets, Product listing ads and News Listings. Each of these pushes the organic listings down and therefore reduce the CTR (Click Through Rate) for all the organic listings.
Therefore, often a keyword with a lower monthly search volume can often be better than a keyword with a higher volume if the organic listings of the higher volume keyword are pushed down by other listings.
Based on the different listings that are shown for a keyword, it is given a number between 0 and 100. The more non-organic listings that are shown above the top organic listing, the lower will be the CTR Scope. Therefore, the higher the CTR Scope the more traffic you can expect to get when you rank in the organic listings.
Keyword Power is one single metric that can be used to compare two similar keywords. It takes into account monthly volume, CPC, SEO Difficulty and CTR Scope. The number is then scaled down to a range of 0 to 100. The higher the score the more valuable the keyword.
The exact formula for this is (Square Root of Monthly Volume) * (1 - (SEO Difficulty)/100) * (CTR Scope/100) * Weighted CPC Value
(The weighted CPC value is obtained by scaling down the CPC values to a range between 0 and 1)
If you are new to keyword research you can use this to effectively filter out keywords and just focus on keywords with a high keyword power.