Talked to Dr. Matt, and he said that, if you just want an estimate, take the log (base 10). You'll get a value from zero to two that will be roughly linear, and then you can scale it up to whatever range you need.

Wow - that's a huge impact. It's hard for me to believe this one change would have such an impact, but hopefully these new numbers stick.

Happy to help - hope it does the trick.

I'm not sure there's a one-sized-fits-all answer. If the .com is more geared to an audience outside of Singapore, and the .edu.sg site is more geared to the local audience you could set a region and/or language with rel="alternate" hreflang:

https://support.google.com/webmasters/answer/189077?hl=en

This is a bit more subtle canonicalization signal that Google can use to sort out sites with language and/or regional copies (the regional aspect may be relevant even if both sites are in english).

The next question would be: where does your traffic come from? If you want to consolidate, but most of your traffic is coming from outside of Singapore, then I'd probably stick with the .com - it still has a "generic" status. The .edu.sg may rank more strongly in Singapore but fall off everywhere else.

I wouldn't worry much about the DMOZ link, especially if you have a solid link profile. DMOZ links have gotten buried over the years and typically don't carry nearly the value most people think. At some point, they could be a solid boost to a new site with a small link profile, but I think even those days are well behind us.

This is generally an exception Google supports - for example, they say that you can use rel=prev/next and rel=canonical in conjunction, where one handles pagination and the other handles sorts/filters. In the case of a sort (like ascending/descending) the actual results could be very different, but the intent is still legitimate. They generally understand you're trying to clean up these pages.

In a perfect world, these filters wouldn't create unique URLs, honestly, but now that they already exist, you have to manage them. The other option would just be to META NOINDEX those filter URLs or set them up in parameter handling in Google Webmaster Tools. I tend to prefer the canonical here, personally.

Good point by Kevin, too, that it does depend on the rest of your link profile and how solid it is. If you have thousands of linking root domains, just one domain isn't going to make or break you. Your overall profile is the key.

First, to Kevin's question, a high DA doesn't mean a site isn't spammy. It means the site has a lot of seemingly high-authority links (or just a large link profile from generally large sites, or a healthy mix). Some of the modelling controls for quality, but not necessarily spam factor - which is something we're actively working on.

I suspect the "articles." sub-domain carries less authority than the overall root domain, but it's tough to say. With so many links, you're probably getting some credit from the root domain.

Unfortunately, the weight of any one link or even 2,000 links from one domain is almost impossible to measure. So, it comes down to a risk/reward scenario. Are you just proactively cleaning things up, or are you fighting a serious fire, like an outright penalty that's killing traffic? If you're being proactive, I'd probably leave this alone, especially if you have solicited these links, paid for them, etc. If you're fighting a serious penalty, then you need to risk cutting deep, especially if you're doing a Penguin recovery.

I tend to agree with Federico's concerns. If the 301 transfers a penalty, the impact could be long-term, and it could be harder to rescue site B. The short-term ranking gains may not be worth it.

Google hasn't been clear on how this operates with 301 redirects. John's suggestion to disavow on both sites seems safe. Worst case, it's wasted effort, but it's not much effort (once you've built one file, building two is easy). Still, you've got to wait for that to process, and if the algorithmic penalty is something like Penguin, then you'd have to wait for a data refresh. This could take months, so I'd be really hesitant to risk site B until you've cleaned up the mess.

Once you disavow to site A, the 301-redirect should be fairly safe, but it does depend on the extent of the penalty. The risk/reward trade-off is definitely a "devil is in the details" sort of situation.

Cross-domain canonical is the most viable option here. As Mike and Chris said, it is possible for Google to ignore the tag in some cases, but it's a fairly strong suggestion. There are two main reasons I'd recommend it:

(1) Syndicated content is the entire reason Google allowed the use of rel=canonical across domains. SEOs I know at large publishers have used it very effectively. While your situation may not be entirely the same, it sounds similar to a syndicated content scenario.

(2) It's really your only viable option. While a 301-redirect is almost always honored by Google, as Chris suggested, it's also very different. A 301 will take the visitors on the partner site page directly to your page, and that's not your intent. Rel=canonical will leave visitors on the partner page, but tell search engines to credit that page to the source. Google experimented with a content syndication tag, but that tag's been deprecated, so in most cases rel=canonical is the best choice we have left.

Sorry, I don't think we're clear (judging by other responses) on what you're trying to check. Are you looking for some core stats on those 800 domains, or do you have a list of keywords for each domain that you want to check rankings for? If it's a list of keywords, how many total (ballpark) keywords are you talking about?