Google CEO Larry Page trotted out an impressive statistic during last week's quarterly earnings call: Google+ now has 90 million users, double what it had three months ago. Even better, 60 percent of those users are engaged daily, and 80 percent weekly.

But those users aren't necessarily engaging with Google+. Any action taken during a logged-in Google session—whether it be searching the Internet, checking Gmail or using Google Docs—counts as engagement under the statistic Page used. Google has refused requests from journalists and interested bystanders to reveal exactly what percentage of those 90 million signed-up Google+ users actually view Plus content each day, week or month. Instead, Google is arguing that it doesn't matter: Google+ is so integrated into the overall experience that what matters is the number of users interacting with any Google site. Combined with other steps Google has taken to integrate Plus into search results and other Google properties, the message is clear: Eventually, Google Plus will just be there whether you want it to or not.

Facebook has 800 million active users, and 50 percent of them log in each day, an impressive feat given that Facebook is really just one site (albeit one with hooks into many other websites). Given the vast number of services Google offers, and the simple fact that Google performs a large majority of Internet searches, it's not surprising that most Plus users interact with Google sites each day. It would be hard for them not to.

Still, 90 million people signing up for a service in just over six months is a big number, a quite impressive one if it was all due to organic growth—people consciously deciding to create a Google+ account and use the site in the same way they've done with Facebook and Twitter. But it turns out the act of creating a Google+ account is often just an incidental byproduct of signing up for other Google services.

On Friday, the Google Operating System blog (not affiliated with Google) wrote a post titled "New Google Accounts Require Gmail and Google+." While this isn't strictly true, the blog demonstrates how Google is making it difficult for new users not to sign up for Google+.

"If you try to create a Google account from Google's homepage, you'll notice that Google redesigned the page, but that's not all. You'll now have to create a Gmail account, a Google Profile and you'll automatically join Google+," the blog states. "Until now, creating a Google account was quite simple. You could either use an existing e-mail address or create a Gmail account. The redesigned form includes new fields: name, gender (required for Google+) and mobile phone number (not required)."

One exception is that Google+ accounts are not created for users who are under 18 years of age.

Another story on the matter states that the new signup process was put into effect Friday. But it's actually been in place for a couple of months. We checked with Google's public relations team on Friday, and were told that the new signup process was rolled out in November. That helps explain why Page was able to announce such a large increase in the number of Google+ signups, while avoiding any mention of how often people actually use Google+.

"We hadn't changed our Google Accounts sign-up flow in more than seven years so it was due for a refresh," Google tells us. “We're working to develop a consistent sign-up flow across our different products as part of our efforts to create an intuitive, beautifully simple, Google-wide user experience. Making it quick and easy to create a Google Account and a Google profile enables new users to take advantage of everything Google can offer."

Google notes that once you've signed up, you can delete your entire Google account, or just your Google+ profile in the account settings page. As for Android, a Google spokesperson tells us the latest version of the mobile OS lets users sign up for Google+ when creating a Google account, but it's optional.

The Google Operating System blog also notes that the old Web-based signup page, which doesn't force you into Google+, still exists, and you can access it if you know the URL. This process lets you create a Google account, including Google Docs access, without being forced to create a Gmail address or Google+ profile. We asked Google if the company will continue to maintain this older, more limited signup page, but didn't get an answer.

Testing the signup process: Is Google+ avoidable?

We tested out the new signup process to see if there's any way to avoid creating a Google+ account. The process is the same whether you start from the Google home page, or Gmail. Once you've clicked "Sign up for a new Google Account," you're already almost halfway through the process of creating a Google+ profile. The signup screen allows you to uncheck a box that says "Google may use my account information to personalize +1s on content and ads on non-Google websites," but doesn't give you the option to decline creating a Google+ account.

The second screen tells the user "Now that you have a Google Account, create your Google profile." There are only two options: "Add profile photo" or click "next step." There is no "skip Google+" option. Clicking either available option results in the creation of a Google+ account, which is by default public and discoverable in Google search results.

The way to avoid creating a Google+ account is to close the browser tab. If you've done that, you can open another Google page and log in, and you'll have a Google account without a Google+ profile. Basically, you must abandon the signup process halfway through in order to create a Google account without an accompanying Google+ profile, which certainly is not intuitive.

You can go into settings afterward and delete the Google+ account. Otherwise, every time you visit a Google site an icon linking to your Google+ profile is on the top right of the screen.

UPDATE: As some readers note, Google has a policy barring use of pseudonyms on Google+. We've noticed in further tests of the signup process that using obviously fake names can prevent creation of a Google+ account. However, Google said a few months ago that it will allow pseudonyms on Google+ at some as-yet-unrevealed future date.

Shaky statistics make Google+ activity difficult to quantify

The point is not to say that signing up for Google+ is a bad thing. At Ars, we've found Google+ to be an effective platform for interacting with readers. Like Twitter, Google+ seems to attract a large number of tech-savvy professionals, and it has some useful methods for dividing and sorting contacts.

And, the new signup process encompassing all services has its advantages. Once you've completed the process from the Google homepage, you automatically have accounts with Google+, Gmail, Picasa, Google Docs, and more. That is convenient—although it would be nice if you were provided the list of services and the ability to choose which ones you want (and don't want) prior to completing the process.

Google+ is still quite new, so we wouldn't expect it to be challenging the popularity of Facebook already. But Google's method for expanding membership can capture a large number of "users" who barely ever visit the site, and Google has a habit of presenting statistics about Google+ usage in a misleading way during its quarterly earnings calls. Thus, the numbers provided by Google so far aren't all that useful for quantifying how active Google+ really is.