p>Experts have long debated just how big your professional network should be. Should you focus more on the quantity or quality of your relationships? The easy answer, of course, is "both." Unfortunately, though, there are only so many hours in the day. Building and maintaining relationships take time; building stronger relationships takes more time.

Given that your time is limited, the number of your relationships and the average strength of your relationships end up being inversely proportional. The more people you know, the less well you know them. If you want to build stronger relationships, you're going to have to do so with a smaller number of people. You can spend all of your time with your close friends and family (strong ties, low number), or spread yourself thin across a wide number of people (weak ties, high number). However, maintaining both high strength and high number is physically impossible. How can you find the proper balance between strength and number?

This debate has been exacerbated by the proliferation of social networking sites that make it feasible to have a personal "network" of several thousand people. The leaders of some of the networks have taken some strong stands on the issue:

• Thomas Power of Ecademy says, "Go for volume over 'quality,'" arguing that there's no such thing as a quality person vs. a non-quality person. He walks the talk -- he's personally met with several thousand Ecademy members one on one.
• At the other end of the spectrum, Mike Walsh, CEO of Leverage Software, says, "Look for quality," and encourages people to look for networking sites with features that help you evaluate whether a certain contact is worth pursuing or not.
• And Adrian Scott of Ryze, discussing some changes in Ryze's policies and functionality, said, "We'd like to create an environment that encourages quality, rather than quantity for its own sake."

Those absolutes are difficult to sustain in practice. For example, LinkedIn very strongly positions itself on the quality of its membership and encourages members to focus on people you've worked with before in some capacity. Their tips on who to invite say:

• Only invite those you know well
• Only invite those you trust
• Only invite those you want to forward things to you

But at the same time, the design of the site encourages people to maximize their number of connections. The more people you're directly connected to, the fewer number of degrees away you are from people, on average. With more direct connections, you can see more people, more people can see you, and you're more likely to come up at the top of searches, which by default order the results by "degrees away from you." The FAQ may encourage quality over quantity, but in practice, quantity is also rewarded. This is a fundamental tension in LinkedIn's design. What allows LinkedIn to still be a valuable application is that quantity also carries a cost: more link requests which you are likely to reject. Some of the most-connected people on LinkedIn have complained about the number of irrelevant requests they're getting. That's exactly the way the system should work; those people are paying the price for linking indiscriminately.