Google PageRank is arguably the most misunderstood and misused Web analytics metric. However, despite the fact that SEOmoz Page Authority is more useful in many respects as a numeric metric  for evaluating how important a page is on the Web, I continue to include PageRank in reporting to clients on the link popularity of their Web presence. Page Authority reports are available at Open Site Explorer.

As background, the following is an excerpt on Google's definition of PageRank:

"PageRank reflects our view of the importance of web pages . Pages that we believe are important pages receive a higher PageRank and are more likely to appear at the top of the search results.PageRank also considers the importance of each page that casts a vote, as votes from some pages are considered to have greater value, thus giving the linked page greater value."

Here are a sampling of reasons that Page Authority is the better metric for evaluating a web page's link popularity:

1) Page Authority is current.
Google PageRank has essentially not been updated since April 2. Changes to link popularity that have occurred during the past four months are not reflected in current PageRank scores. In the past, PageRank was updated approximately quarterly. However, the dates for future updates are unknown and seemingly arbitrary. Based on the timing of past updates, the next round of revisions is quite overdue. Further, I cannot completely dismiss the conspiracy theory like speculation that the last two updates were released around holidays to minimize the attention they received.

On the other hand, Page Authority is much more current as it was updated on August 16 and SEOmoz has already announced that the next update will occur in September.

2) Page Authority is more precise.
Google PageRank is on a 1-10 scale. Thus, if your site has a PageRank (PR) of 4, it requires significant enhancements to link popularity to move PR to a 5, making progress hard to measure. The bluntness of the grading scale also provides little value in determining if a competitor's link popularity is changing. Page Authority's 1-100 scale provides much finer gradations. It is possible to measure smaller changes and much more useful as a trend measuring tool. I have a couple of clients, Koffler Sales and InstallationTools, for whom their home page PR seems to be stuck at 3. It is far more interesting on a trend basis to report on their monthly changes versus competition based upon Page Authority..

3) Page Authority provides more depth of information.
PageRank is simply reported as a stand alone whole number without any qualifying information. Further, since a 1998 paper published by Brin and Page, enhancements to the algorithm are closely held secrets. Google is totally opaque in regard to how PageRank is currently calculated and enhancements since 1998.

In comparison, a viewing of a Page Authority report on Open Site Explorer also provides results for Domain Authority, Linking Root Domains, and Total Links. Further, numerous SEOmoz blog updates provide transparency into how the Page Authority metric is calculated and the ongoing updates to the algorithm.

4) The reliability and quality of Page Authority is getting better due to continuous upgrades.
The value from Google PageRank is being devalued and denigrated by Google employees. Here are quote from the Google Webmaster Help and from a Google employee:

"We only update the PageRank displayed in Google Toolbar a few times a year; this is our respectful hint for you to worry less about PageRank, which is just one of over 200 signals that can affect how your site is crawled, indexed and ranked. PageRank is an easy metric to focus on, but just because it's easy doesn't mean it's useful for you as a site owner."

"We've been telling people for a long time that they shouldn't focus on PageRank so much; many site owners seem to think it's the most important metric for them to track, which is simply not true. We removed it because we felt it was silly to tell people not to think about it, but then to show them the data, implying that they should look at it".

Compare Google's downplaying of PageRank to frequent the updates from SEOmoz on Page Authority and Domain Authority. The most update was an August 27th announcement of further improvements. Obviously, Page Authority is getting a lot more tender loving care than PageRank. 

After reviewing factors that make Page Authority a more valuable metric, one might ask why I still report on PageRank to clients. There are four  reasons why I continue to report on PageRank: 1) it is a term that has been bandied about so much that clients recognize the name; call it a  legacy effect. A number of my client probably expect PageRank to be included in tracking reports; 2) Being published by Google provides this metric with perceived authority. Clients tend to trust it as a metric; 3) Although the published PageRank numbers are out of date, PageRank remains a highly important factor in how many pages on a site are indexed by Google and as it is an important factor in the ranking algorithm, and 4) as Rand Fishkin indicates in regard to Page Authority and Domain Authority "this metric flops around, but we also think it's important that we're as "honest" and accurate about it as possible - today it's still in infancy, and likely needs many more such updates and improvements before achieving consistency."

Conclusion

Google PageRank and SEOmoz Page Authority are both valuable metrics in determining link popularity. However, if Page Authority is not already the more useful metric, it is on the verge of becoming so. But don't discard Google PageRank yet. It remains the metric that is most likely to resonate  with clients and remains the gold standard among link builders. Educate clients about both tools, and take advantage of having two numeric metrics to use to evaluate and report on link popularity.