This is the final post in my PageRank vs. MozRank discussion. In Part 1, I busted some of the myths and misconceptions surrounding Google’s PageRank. In Part 2, I explained how the biggest contender in the page/domain metrics game, SEOMoz’s mozRank, measured page and domain trust and authority.

As a long time SEO and SEM guy myself, I have some pretty strong opinions concerning toolbar PageRank and the hold it has over a lot of stakeholders and marketing professionals. Even though the consensus among SEO professionals is that toolbar PageRank is not an accurate way to measure much of anything, it continues to be seen as an important indication of site strength and authority. Fortunately, this appears to be changing as more major players ditch PR in favor of mR.

Over the course of writing these posts, I have narrowed all of the variables down to  three major factors. I believe these factors are the big ones that should concern anyone that is actively monitoring site trust and authority of their own domain or of domains that they are linking to or from.

1. Data Reliability

PageRank – The only way to measure PR is through the toolbar which only displays whole numbers. This is completely useless when the scale is logarithmic and the distance between the whole numbers grows exponentially as you move up the scale. PR is updated rarely, often going 4-6 months between corrections. Until recently, updates to PR were almost never communicated beforehand.

mozRank – SEOmoz is in the SEO metrics business and having reliable tools are their bread and butter. Updates to the Linkscape index are scheduled in advance and SEOmoz does a pretty good job of sticking to their goal of updating every 4 weeks.

2. Data Availibility

PageRank – Google has never provided a method for obtaining PageRank via an API. This has always presented difficulties for developers of web analysis tools as they must use their own methods to obtain PR and are essentially violating Google’s TOS by doing so.

mozRank – SEOmoz provides a free and paid version of their API and ample support for developers who wish to incorporate mozRank into their own tools.

3. Domain & Page Level Metrics

PageRank – There is no method of using PageRank to measure the authority of a domain as a whole. Many people wrongly assume that the home page PR is somehow indicative of the domain as a whole but that is not the case. The home page just happens to be the page with the most inbound links on most sites.

mozRank – MozRank and mozTrust are based on and work similar to PageRank. They measure authority and trust for single pages. SEOmoz also offers a variety of page and domain related metrics. This allows analysis of a much broader range of factors that are important when developing a link strategy, researching competitors, or when considering the purchase of a site.

So, who is the winner? I think that, after considering all of the factors, it is pretty safe to say that mozRank provides a more accurate measurement of authority. What do you think? Does PageRank still matter in your world?