I once sat in front of a dark, Netflix-enabled flat-screen, watching Netflix on my iPhone. It was just easier, and I had it on, and I could switch back and forth with Facebook, and… ok, maybe I have a problem!

In any event, our personal fascination with mobile phones shouldn’t dictate our work decisions. And one question that needs deciding more and more these days is around mobile search: is there a mobile audience for this particular client? And how do we measure the success of our efforts to get a mobile website in front of mobile searchers?

Of course, our past experience with desktop search gives us a great starting point. Search volumes, traffic, and even rankings are useful metrics, both here and there. But mobile SEO brings some special considerations, not least of which is credibility: we need to prove that mobile SEO provides value.

To that end, I’ve been working on a set of metrics to help me get some perspectives on these questions. These aren’t replacements for visitor counts or conversions – rather, think of them as supplements to help us compare the new and somewhat unfamiliar mobile SEO data to our tried-and-true desktop data.

Today we’ll look at one of the most useful, particularly in the early stages of a campaign.

The Mobile Ratio

One of the challenges in getting started with mobile search is proving the value of your efforts: is anyone using a phone to search for this client’s products or services?

To answer that with a simple, understandable metric, I’ve added a Mobile Ratio to the keyword research process. Basically, I’ll start by taking a desktop keyword list, and running the numbers to add mobile figures alongside. I’ll also expand the list if I find any mobile-specific keywords that seem interesting.

Then I’ll take the desktop and mobile volumes, and divide one into the other to compute the Mobile Ratio. For example, if I have a Mobile Ratio of 10, then I can tell the client that for every ten desktop searchers, we have the opportunity to reach one mobile searcher.

Straightforward statements like that allow a client to get their bearings, and start to form a mental model of what mobile means to them. Maybe they’d really like to add another one-tenth to their reach. Or maybe they have easier ways of getting access to those extra eyeballs. Either way, they now have some useful infomation on which to base a decision.

Getting Granular

Doing this at both the keyword and aggregate level allows you to compare and contrast mobile activity for different keywords. So if my aggregate Mobile Ratio is 10, but I have a group of keywords that have ratios in the 5-6 range, then I know these keywords are mobile-heavy: they are more likely to be of interest to mobile users.

This is key info for site-planning and budgeting activities, as it can provide a business justfication for heavying-up on landing pages that address those keywords. Likely examples of keywords that are mobile-heavy could include coupon keywords, or keywords that include a location name.

The Mobile Ratio lets you identify keywords that are mobile-heavy. Here, "pocket knife" searches are strong, while branded searches ("Victorinox") are relatively light. Good inputs for planning a mobile content strategy. (Not one of my clients, by the way.)

Driving Strategy

In the end, the Mobile Ratio doesn’t create another data point. Instead, it offers a more intuitive way of looking at the data you already have, turning it into a KPI that you can use to make decisions about your mobile marketing plans.

In upcoming articles, we’ll take a look at some other useful metrics for managing mobile SEO.

Dim Sum Versus Steak

Let’s start with user needs. Jacon Nielson recently published a study confirming that bite-size chunks of content are best for mobile users. “When in doubt, leave it out” was his sound-bite takeaway. Given our own personal experience with small screens and choppy bandwidth, his conclusion seems pretty intuitive.

But bite-size content clashes with our ability to optimize and promote these pages to search engines. We need more copy, not less, to be able to insert keywords and get traction for a variety of terms.

As we saw last month, Amazon splits product information into two mobile pages.

Amazon’s mcommerce site tries to solve this problem by providing a very short on-page description, and then linking to a second page for more details. This satifies usability, but isn’t ideal at all for search. That second page has all the content, but the first page is likely to have better link authority.

Fortunately, there’s a solution that was developed to solve other sorts of design problems, that can also be helpful for mobile SEO.

Introducing JQM

JQuery Mobile (JQM) is a JavaScript library that was built to close the gap between mobile sites and native apps. Apps typically have the advantage when it comes to interactivity, taking advantage of a library of user interface elements, and offering seamless screen-to-screen transitions.

JQM was built to take advantage of the latest HTML5 and CSS tricks, to help Web designers close the gap with their app developer counterparts.

I published a review of JQM on Search Engine Land back in April, when it was still in alpha and under heavy development. Version 1.0 finally launched last month, and fulfills on the promise of providing app-like capabilities that work on any smartphone – build once, use anywhere.

Leveraging JQM For SEO

One particular aspect of JQM will be useful in solving our content issue. The platform provides a number of options for loading new webpages into a phone, giving designers the ability to import content without keeping a user waiting for a download.

The option of interest to us is called “Internal Linked Pages.” JQM allows multiple pages to be packaged as one big file, where the “links” between pages simply drag the new content into view.

To the user, a new “page” has been loaded – but in reality, that page was already downloaded to the phone, waiting to be viewed. The plus for SEO is that search engine spiders will also download this batch of small pages as a single large file – one that appears to have a decent amount of indexable content.

See the video, starting at 3:05,  for a demonstration of how JQM behaves on a phone:

Click here to view the embedded video.

Combine these capabilities with a strategy for developing mobile commerce content, and the result will be a store that’s not only easy to use, but easy to find on Google as well.

Search for Groupon, eBay, Amazon, Target, QVC or numerous others. Alongside the brand website listing, local listings, and social profiles, searchers are starting to see links to these brands’ iPhone, iPad, and Android app profile pages, right on the first page of Google.

These app page URLs are presenting powerful new opportunities to “occupy” Page 1 of Google SERPs for desktop and mobile searchers, with big payoffs.

eBay's iPhone App Page Ranks #2 in Google for "eBay"

Optimize App Popularity Through Organic Search

The opportunity is really the product of a collision between Desktop and Mobile worlds: the explosive popularity of apps are reshaping the Web’s link graph around the App Store and Android Market sites.

It comes as no surprise that “Popular Apps” listed in the App Store and Android Market pages are driven by app download volume and rating quality. But these app profile pages and app “directories” (like the App Store’s Lifestyle category page) are also webpages.

As search engines continue to index, display, and rank app pages for search-dominant mobile users, app-mania is simultaneously driving  a geometric expansion of the backlinks and social popularity of these ordinary webpages – giving them extraordinary influence over organic search results.

The net effect, based on our own analysis of top ranking mobile iOS apps, appears to be a powerful feedback loop: App Store popularity gets rewarded by incremental Google visibility.

Higher Google visibility induces more app downloads. More downloading drives higher App Store popularity… and on and on, potentially entrenching popular apps in a rich-get-richer-faster phenomenon:

The App Visibility Cycle (courtesy of pureoxygenmobile.com)

This might seem like bad news for the 99% who have good mobile apps, but aren’t among the “Most Popular” apps listed. But the fact is, this highlights the opportunity – and urgency – for brands to optimize app pages for organic search rankings, to help drive app popularity and other benefits.

Here are five Mobile App SEO tips to get started optimizing your apps for Page 1 Google rankings on brand queries:

Tip #1: Feature your brand prominently in the app name

The app name doubles as the link anchor text within the App Store and Android Market. Getting these sites to link to your app profile page, using your brand name as a link, is critical for tapping into their enormous link equity. (See Groupon, Amazon, and eBay examples below.) Be sure to feature the brand name in the download page URL as well.

Groupon, Amazon, and eBay: Their App Profile Pages Feature the Brand Name as Link Anchor Text

Tip #2: Link to your app profile page(s) from your home page and/or site footer

You have to aim the link equity of your most important pages at your app download pages. Many brands bury these important links.

Consider building a landing page or section dedicated to your apps with screen shots, reviews, features, etc. But it must also have links from the most important pages of your site, and follow the other tips here to make it into Page 1 for brand queries (REI does a nice job of linking to the REI apps).

REI's internal landing page promoting iOS and Android Apps

Tip #3: Include your brand name in the link text that points at app download pages

Too many brands make the mistake of linking to the app profile page without including the brand name, as in  “Download iPhone App.” Even worse, some just link through the “Available on Android/App Store” graphics. (See Walmart example below.) This is a huge missed opportunity! Use your anchor text wisely.

You have to signal that App Store or Android app page is all about your brand (as in “Download the Walmart iPhone app” or “Get the Walmart App for Android.”)

Walmart Links Graphics (No Anchor Text) to App Profile Pages

Tip #4: Provide a QR link to download the app from your desktop site landing page

Use QR codes to give desktop site visitors easy app access. The QR needs to trigger app download on the right device once scanned. Remember to compress the link before your generate the QR. Native Apple and Android app page URLs exceed 50 characters, producing high-density QRs that fail to scan when displayed at small sizes. (Notice the Walmart example above.)

For best results, use a link compression or QR platform that shows you bot QR crawl requests (full disclosure: we provide one). Our prediction is that QR will be a mobile search ranking signal within the next 12 months. Start experimenting now.

Tip #5: Cross-promote your app to mobile users, searchers, and bots

Here’s the magic. You already have a captive mobile audience itching for you to make it easy to discover relevant mobile pages (or your app).

When iPhone, iPad, or Android browsers hit your site (desktop or mobile), provide a link at the top of the page for them to download the appropriate app for their device. (Let’s assume your desktop pages indexed in search engines properly redirect mobile searchers to appropriate mobile pages. If you’re not sure, find out.)

But don’t stop there. For the trifecta, make sure Google’s new Smartphone Googlebot is crawling the app links from your mobile pages as well, using appropriately branded anchor text (not images).

Amazon's Mobile Site Promotes the iOS and Android App, But Lacks Anchor Text

App Store and Android Market app pages are a powerful new ranking opportunity for desktop and mobile searchers. Retailers and media brands with large volumes of site traffic, page content, link networks, or social popularity, can easily leverage these digital assets to influence app profile page relevance, and app popularity, at the same time.

Merry Christmas to all. See you in 2012.

Today and for the next few days people will be using a wide range of tools and resources — hopefully not pepper spray — to help them determine what and where to buy to get the best prices on items on their holiday shopping lists. This year there are more tools, sites and mobile apps than ever it would seem. Indeed, there’s just no way to deal with all the online shopping sites and apps comprehensively in one post, but here’s a sample of what’s out there.

Search: where it all starts

Google just this week beefed up its Product Search site with a number of new features and capabilities. Product Search now has more information and is much more “visual” than it used to be (courtesy of the shuttered Boutiques.com). The home page of Google Product Search doesn’t feature any Black Friday specific information but it does promote Google Offers, the useful Google Shopper mobile app and the recently relaunched Google Catalogs for the iPad.

Google Product Search and Google general search results also show information about where you can buy items in stock at nearby stores. This is a nice feature of Google’s product search that isn’t available on Yahoo or Bing.

However if you’re looking for Black Friday information Google Product Search isn’t a great place to start. Yahoo has much more Black Friday content, including a dedicated deals site with Black Friday and Cyber Monday deals. All same information is also accessible from the main Yahoo Shopping site.

You can browse all the Black Friday ads online in one place on Yahoo, albeit in a somewhat awkward scanned-pdf format. Probably the best place to see all the Black Friday Ads in a browse-able and searchable format is ShopLocal.com. It’s not a great user-experience but it gets the job done. The Black Friday sites also have all or almost all the ads online as well.

Not as good as ShopLocal but better than Yahoo, Bing does good job with formatting and presenting the weekly “circular” retailer information, including Black Friday ads. However the “circular” information is unfortunately quite limited. Luckily there is a dedicated Black Friday-Cyber Monday section in Bing Shopping that also features some editorial picks.

You can, of course, also use Google, Yahoo and Bing to search for “Black Friday Ads” or “Black Friday Deals” sites. There are dozens of them (e.g., BlackFriday2011).

Shopping engines: Amazon, eBay and beyond

Amazon is the most aggressive of the online shopping sites, with loads of Black Friday specials including hourly “lightening deals.” Amazon also has a range of iPad and mobile apps for your cross-platform shopping convenience.

These include Windowshop for the iPad, the Amazon Mobile app and several other mobile apps. For example Amazon Deals allows you to rapidly flip through Amazon’s Gold Box and Lightening Deals on your smartphone. There’s also Amazon Price Check for in-store price comparisons.

Amazon rival eBay is also featuring Black Friday deals and daily deals on its home page. PayPal, which is owned by eBay, also has shopping and deals. However, PayPal mainly uses email to promote shopping to its existing users. There are no Black Friday specific promotions apparently.

There are numerous mobile apps from eBay including RedLaser, a barcode scanning app that offers an expanding array of content and functionality (i.e., pricing, reviews and local inventory data). The local inventory data is from eBay’s Milo.com and is available online (though buried) and through a dedicated Milo mobile app, in addition to RedLaser.

Shopping comparison engine PriceGrabber has a Black Friday-Cyber Monday section. Nextag is also offering some Black Friday deals. However most of the shopping engines seem to be sitting out Black Friday-Cyber Monday in terms of specific promotion. That includes eBay’s Shopping.com. As an aside, one of the best sites for general online shopping and price comparisons is TheFind, which also has a mobile app and a local store inventory finder.

Mo-Lo: mobile apps and local inventory sites

In addition to those already mentioned there is an ever growing list of shopping-related mobile apps. Most major retailers now have mobile apps, which typically include sale and deals information. And most of them will have their Black Friday deals there too. There are also at least 10 Black Friday specific mobile apps in the iTunes store right now, the highest rated of which is TGI Black Friday.

ShopSavvy is another mobile app that offers deals, as well as local store inventory data and newspaper weekly circular information. The app also features a barcode scanner that accesses price and product reviews content. Goodzer is another site and mobile app that tells you what stores carry products locally. It doesn’t guarantee real-time inventory information, but claims to have a larger catalog of local products than any of its competitors.

There are also a number of mobile apps that offer venue maps to get you efficiently around the mall so don’t get frustrated and have to use pepper spray on your fellow shoppers. Among them are: Micello, Point Inside and FastMall. Point Inside also features local deals content.

Decide.com, from the people who created travel site Farecast (acquired by Microsoft), will tell you whether you should buy a gadget or electronics item now or wait, based on historical pricing data. It also includes a barcode scanner and features product revenues and nearby local inventory data.

Foursquare and Shopkick are running special promotions in conjunction with credit card issuers Amex and Visa respectively. Foursquare’s is part of a promotion tied to “Small Business Saturday,” which sits between Black Friday and Cyber Monday.

Most of the above-mentioned apps are also available in the Android Market.

Deal sites: where every day is Black Friday

Among the top daily deal sites only LivingSocial seems to be doing a Black Friday specific set of promotions. Groupon is offering its normal deals. That generally seems to be the case for the other major deal and “flash sale sites” that I checked.

However Groupon anticipates a big holiday season and expects that consumers will be giving deals (in the form of services and experiences or Groupon purchase credit) in addition to more traditional gifts.

That’s more than enough information to digest. If I were to write more and you were to spend more time reading this you’d be delayed in getting out there and grabbing the deals before they’re gone. However if you’re reading this on a mobile device you may already be in the store or in a checkout line.

Some people have already been shopping all night. But if you haven’t started yet, here’s a little taste of what you may be in for: SNL’s mock Black Friday ad from last season.

The company says it serves 10 billion monthly ad impressions. The data in the report were collected between July and September. Here are a few key points:

• 37 percent of general mobile consumers use their devices for local search, while 75 percent of smartphone owners conduct local searches (Google has reported even larger numbers)
• Local search growth on xAd’s network has seen triple digit increases this year (with faster growth concentrated in apps vs. the mobile browser)
• xAd sees 90 million local-search requests per month and over 250 million local-search requests per quarter
• 62 percent of users conduct at least two local searches per month, while nearly a third (32 percent) of users do at least five local lookups per month
• Tuesday and Wednesday are the most active days for local-mobile search, which peaks generally during the middle of the day

The top local search categories or lookups seen on xAd’s network in Q3 were the following:

1. Restaurants
2. Gas stations
3. Shopping
4. Auto repair/dealers/rentals
5. Fast food
6. Cafes/coffee shops
7. Travel & lodging
8. Health & medical
9. Bars & clubs
10. Finance & legal

The network also reports on engagement and ad performance data, both in terms of apps vs. browser and iPhone vs. Android. The report indicates that CTRs on ads in apps are 8 percent vs. 5 percent for browser.

Call-through rates, however, are higher on browser-based ads. This difference is attributed to feature phone users calling businesses rather than seeking more information on their handsets, which offer a more constrained user experience than smartphones.

The company reported that CTR rates on the iPhone and Android are roughly comparable, but that “secondary actions” are greater on iOS. These secondary actions can include calls, map/directions access, review lookups and so on. Calls are the most popular “post-search” secondary action (62 percent), followed by maps and directions lookups (35 percent).

The xAd report also discusses demographic data. As one might expect, the heaviest users of local-mobile search tend to mirror smartphone demographics generally: a slightly more male audience (55 percent), concentrated in the 25 to 44 age range, which is also more affluent ($75K+) and educated than the general mobile population.

But what is the official Google stance on mobile sites, search and SEO? Will having mobile content help in search results?

Many people will claim that Google has offered an official position on mobile search and SEO, but they don’t realize that someone else in Google has offered a different, sometimes even contradictory, position on the subject.

How many stances have people from Google offered on webmaster issues related to mobile search? Eight, by my count.

1.  Matt Cutts On Mobile Duplicate Content & Mobile URLs

In January of this year, Matt Cutts answered a question about mobile SEO and recommended using a mobile URL for testing purposes with URL redirects for Googlebot mobile for the mobile site and Googlebot for the desktop site.

He didn’t address smartphone users, who are the most active mobile users. He did, however, say one thing that Google has been consistent about: mobile content is not duplicate content, and if you redirect it to the appropriate bot you won’t be seen as cloaking. He reiterated this stance in his most recent video on cloaking.

2.  Google SEO Guide, Google Japan On Redirecting Mobile Content

The advice that Matt Cutts offered about redirects was taken from the Google Japan team, who in late 2009 recommended redirecting feature phone users to mobile sites through redirects.

This advice was reiterated in the section on mobile SEO in the Google SEO Starter Guide, published almost a year later, and illustrated above.

3.  Redirecting Traditional Mobile Content But Not Smartphone Traffic

When it comes to redirects, in February of this year Pierre Far of the webmaster team made a distinction between smartphone traffic and traditional mobile traffic that wasn’t made before.

He said that webmasters don’t need to do anything special for smartphone users, but it may make sense for some websites. He also said mobile sitemaps are not for smartphone URLs, but for traditional mobile URLs.

4. Redirecting Smartphone Traffic To Mobile Sites & Tablet Users To Desktop Experience

A little more than a month later, Maile Ohye of the Google Webmaster Team said that it’s reasonable to drive Android users to your mobile site, but that you should direct Android tablet users to your desktop content, and smartphone users to your mobile content.

But didn’t Pierre Far just say no redirects were necessary for smartphone searchers?

5. Google’s John Mueller On Single URL Mobile Strategy

John Mueller of the Google Webmaster Team took questions on his Buzz page (now on Google+) in which he recommended a single URL mobile strategy for smartphone content in order to reduce redirects and make the experience faster for mobile users.

He then clarified his position on Search Engine Roundtable, saying “If the touch.example.com site is significantly different that it covers a special niche, then maybe that’s ok [to index separately and not add rel=canonical to].”

• Update – John Mueller later said on his Google+ page that either mobile URLs or desktop URLs formatted for mobile are fine with Google.

6.  Providing A Fast, Relevant & Simple Mobile User Experience

In late June of this year, Google’s search quality head, Amit Singhal, said that Google is hyper-focused on getting the mobile user experience right in mobile search, and didn’t make a distinction between mobile search being feature phone as opposed to smartphone traffic.

He said that Google focuses on making a fast, relevant and simple mobile user experience, and that’s why they’re poised to excel at mobile search.

In March of this year, the Page Speed team also said speed is more important for mobile users.

7.  Google’s Scott Huffman On Blended Mobile Ranking Algorithms

Google engineer Scott Huffman revealed in Searchology 2009 that Google has ways of presenting content that they think is more relevant to mobile users for certain queries than desktop users, and confirmed this in a New York Times article this year.

Separate tests by Resolution Media and Covario both confirmed that mobile smartphone ranking differs from desktop rankings. Yet it’s unclear whether having mobile optimized content is actually a ranking factor in mobile search, since Pierre Far and others claim that desktop sites are adequate for smartphone browsers.

8.  Building Mobile Specific Content Rather Than Transcoding Desktop Experience

The most recent Google employee talking about mobile is probably Avinash Kaushik, who gave a fantastic webinar recently called Re-think Mobile Marketing & Analytics.

The webinar focused on creating extraordinary mobile experiences that add to the brand value rather than detract from it. His basic premise was to create desktop content for desktop users, mobile content for mobile and smartphone users, and tablet-optimized content for tablet users, and to do it in a way that takes advantage of what that specific device can do.

This is a lot of the same message that we also get from the best practices on the Go Mo site, but it begs the question: if mobile content is so important for mobile users, why does Google show so many unusable desktop results to mobile users in mobile and smartphone search?

Final Thoughts

So there are eight perspectives from Google employees on mobile sites and mobile search. There could be more, but these are the ones I know of. This is why it’s baffling when some writers claim that mobile SEO is a myth because one Google employee gave one opinion. If you really want to understand what Google the organization thinks about mobile sites and search, take the sum total of what they’ve said and try to make sense of it.

Granted, not all of these stances are mutually exclusive.

For example, you could build a fast site with a simple interface that’s extremely relevant to mobile user queries, as Amit Singhal suggests is necessary for mobile searchers, and you could build that on a mobile URL like m.domain.com as Matt Cutts suggests.

However, some of them are mutually exclusive.

For example, Maile Ohye and the Android Dev team say redirect smartphone traffic like the Nexus One to mobile content, but Pierre Far says no redirects are necessary for smartphone content.

Also, if you build a fast site with a simple user interface that’s extremely relevant to user queries, why would you give smartphone users desktop content, which is likely to be slow-going pinching and zooming through tiny text to find a result?

Some clarification is needed here to help webmasters serve the right mobile content to the right searchers, as the answers that have been given so far often cause more questions than answers.

Finally, I’m not suggesting that marketers need to wait until Google validates our mobile SEO strategies in order to keep optimizing.

On the contrary, things like doing mobile keyword research to understand how the mobile user experience differs from the desktop user experience and catering your content to that user experience is just good SEO, even though the user is mobile.

But Google, if you’d like to clarify your position on mobile sites, search and SEO, as Bing did last month, the webmaster community might find it easier to digest the sometimes contradictory positions above.

Slightly less than 60 percent (59 percent) of survey respondents said that search engines were the first place they go when researching local businesses. That number increased to 83 percent for those under 35 years old. Less than 10 percent (8 percent) said they visit the merchant’s site first.

On mobile devices, the story is somewhat different. The study found that 17 percent of adults “base their decision” on a search engine when researching a local merchant or restaurant. However, a comparable amount (15 percent) rely on review sites (e.g., Citysearch, Yelp) in a mobile context. Similar to the online findings, fewer than one in ten (8 percent) rely on merchant websites.

So while businesses need an optimized mobile presence, it’s not going to be as critical as presence in local search results and on review sites.

The other piece of data released this morning involved the distance users were willing to travel to try new businesses. The survey found the outside limit to be 30 miles for the majority of respondents. The majority (80 percent) said they wouldn’t travel more than 30 miles to try a new business. But a sizable minority were willing to go more than 15 miles:

• 39 percent said they were willing to go between 15 and 30 miles to try a new business
• 32 percent said they would travel less than 15 miles
• 20 percent said they’d go more than 30 miles

The report focuses primarily on news consumption on tablets. However we know from numerous other studies that tablet owners are also highly engaged shoppers as well.

Tablet owners are more educated, affluent and employed than the general US population. And they’re using tablets to access news instead of their PCs, TVs and print (to a lesser degree). Pew says that people are with their tablets roughly 95 minutes daily. Separate studies have found that tablet usage spikes in the evening and on weekends.

The study surveyed 1,159 tablet users by telephone in the summer and early fall of this year.

Here are some additional findings:

• For 90 percent of tablet news consumers (the 53 percent) it is the preferred news-reading medium, replacing the PC, TV and print. The PC is the primary “loser” in the substitution of tablets for other media
• 30 percent spend more time consuming news than before their tablets
• Only 14 percent have paid for news content specifically on tablets, while a second group (23 percent) have combined print-digital subscriptions. Accordingly paying subscribers for access to news on tablets “may be closer to a third” of tablet owners
• Browser vs. apps: 40 percent get news principally through a browser; 31 percent use both browser and apps; 21 percent get news mainly through apps
• While news-app consumers are the minority (21 percent), they’re more engaged and more satisfied than browser-news consumers. They are also”power users” who consume more news content than others

There’s a good deal more to explore in the full report, and there’s also an infographic with a summary of stats: Infographic: The Tablet Revolution.

Google also sees mobile as a strategic front for social networking growth. The new version of Android (“Ice Cream Sandwich”) prominently features Google+.

The chart below shows comScore traffic estimates for mobile usage of Facebook, Twitter and LinkedIn. Facebook has many more mobile users than the other services, although I assume comScore underestimates the number of actual mobile users across the board.

For example, Twitter recently said it had 100 million active mobile users. It also said, “46 percent of active users make mobile a regular part of their Twitter experience.” That would mean 46 million mobile users at least for Twitter. If 60 percent of Twitter users come from outside the US we can crudely estimate that there are just under 20 million mobile Twitter users in the US.

Overall comScore says the mobile-social networking audience in the US is just over 70 million people. The total mobile internet audience is now over 100 million people in the US according to data from Nielsen.

The same is true for Yahoo. If you say, “Search Yahoo for Wilson Phillips” or “Search Yahoo for Google Earnings” you see these results:

Who knew? Well, if you launch Siri, click the little info button, then select the Web Search option, you’ll find an example listed at the end of how you can ask “Bing Alicia Keys,” it turns out. But most people probably haven’t done this.

Of course if you change your search settings to make Yahoo or Bing the default, Siri will search either of them instead of Google. In that scenario, you could still get to Google by saying “Search Google . . .”

Siri thus emerges as a very efficient way to compare search results or to use a second engine if you don’t like what you get the first time.