How does Facebook determine the six friends that you see when looking at someone’s profile?

Answer by Yee Lee:

Facebook calculates a "social closeness" score for every pair of nodes in its social graph.  They use this social proximity score to rank each person's friends and this ranking is reflected throughout the site — it's used for determining which people's posts show up in Newsfeed, which mutual friends are shown on Profile pages, which people's Likes and social ads are shown in the right rail, etc.

Since the FB social graph changes every day (e.g., as people add new friends), the social proximity score needs to be updated regularly.

The actual scoring algorithm itself is proprietary to Facebook, but is likely based on traditional social graph distance metrics developed in academia.  E.g., Facebook might take into consideration factors like:

• # of friends in common that each pair of people shares (e.g., the number of unique 2-edge paths between any two nodes in the graph)
• the total # of friends that each person has (e.g., if Person A only has 20 Facebook friends and shares all 20 with Person B then A might be considered "closer" to B than, say, to Person C who has 2000 friends and shares 20 mutual friends with A)
• # of interactions between a pair of people (e.g., if Person A and Person B regularly share mentions/comments/likes with each other, then A might be considered closer to B's friends than, say, to Person C's friends where A and C never comment/like each other's posts)
• the type of interactions between a pair of people (e.g., if Person A tags Person B in a photo, that might be a stronger signal of closeness than just having some friends in common)
• pace and recency of interactions between a pair of people (e.g., if Person A has recently checked-in to a location with Person B, that might be a stronger signal of closeness than if they checked-in a year ago and haven't been seen together since)

There are lots and lots of graph structure and interaction signals that can go into a social proximity score!  Note that similar techniques/algorithms are utilized by just about every company that works on social apps and communication products.  E.g., Google utilizes this type of scoring/ranking when they suggest email addresses to include in the "To:" line of a GMail message.  E.g., Zynga utilizes this type of scoring when they suggest friends to invite to a social game.

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If you just missed becoming a millionaire or even a billionaire, do you regret it?

Answer by Yee Lee:

Of course I regret it, how could you not?! 

I was at PayPal pre-IPO and had a chance to work with Steve Chen and Chad Hurley.  Back then, PayPal's product development process was very Product-driven and as a young PM.  I loved that about the place; it was an exhilarating job/experience.

When I was getting ready to leave PayPal in late 2005, I remember having a conversation with Steve about product management positions at YouTube.  He said, "Y'know, we didn't really like the way product managers and engineers interacted at PayPal.  So here at YouTube, we want engineers to lead product decisions.  So we kinda just want PM's to take notes on what the engineers decide and make sure that stuff gets done."

I mulled that over, thought that sounded terrible, shook my head, and told Steve that maybe we should chat again when he was ready to bring on-board a *real* product manager.  I WAS (maybe still am) SUCH AN IDIOT!  I had an opportunity to talk with the founders of YouTube about being one of the first (if not the first) PM and I didn't even engage in the conversation because I had held precisely one (1) product management role before in my life and therefore assumed I had it all figured out…  Sigh.

In hindsight, I think careers in Silicon Valley are so dependent on luck, timing, and who-you-happen-to-know that a lot of us probably have gone through these kinds of near-misses.  In fact, I think that's one of the things that makes the Valley special — the business ecosystem is connected enough here that just about everyone knows someone or has a friend-of-a-friend that experienced major personal career success.  That proximity to success creates a lot of readily available role models and exemplars that drive the aspirations of the whole Valley.  It's not just the top universities, the long tradition of technical innovation, and presence of venture capital or other legal/support functions…   Other countries have tried bringing all those factors together into "innovation hubs" and not been able to replicate Silicon Valley.  It may be because they're missing the social-connectedness and success role models that we have!

I think the regret of a few missed-opportunities is a small price to pay for working in the greatest innovation center on the planet!

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What are some examples of really good backlogs?

Answer by Yee Lee:

Remember: the purpose of a backlog story is just to cause the right conversations between team members.  So, it's difficult for an outsider to gauge the "goodness" of a backlog just by looking at the story headlines. 

In some cases, 1-liner story could be all you need to remind team members of a whiteboard conversation they had.  Usually, though, you'll see a lot of back and forth interaction between team members while they groom a story as it moves up the backlog.  E.g., if you follow a backlog over several sprints, you should see:

1. A story starts off in the Icebox or low down in the Backlog as a 1-liner or a very simple description of the desired user experience
2. As the story moves up towards the top of the Backlog, you may see, mocks/attachments, implementation notes or sub-tasks get added to the story — indicating that the development team has been grooming the story and thinking about how to implement it
3. Ideally, the conversation about "how" will feedback into the "what" of the story and you may notice that stories with broad scopes get broken down into multiple smaller stories that will each get prioritized.
4. By the time a story gets close to the top of the Backlog, it should meet a few criteria:

• Granular enough that a single individual can implement, e.g., no intra-team dependencies for a single story.
• Developers have discussed/groomed sufficiently so that they understand exactly what needs to be done, e.g., if you ask multiple team members what the story is about, you'll get identical answers
• Each development team member has a good enough idea of how they would implement the story that they can give a confident estimate.  Side note on story estimation: development team members typically are pretty good at estimating story points up to the equivalent of a day's worth of work.  Any points estimate that indicates multiple days of work should be taken as a red flag of story uncertainty.  High-performing teams will take the time to do multiple rounds of estimation, breaking down stories until they all fit under a low points-ceiling.

Here are a couple public examples of backlogs for on-going, active projects…

Jasmine JS:
https://www.pivotaltracker.com/s…

The agile backlog used to build the Jira Agile app (how meta):
JIRA Agile (formerly GreenHopper)

And if you google around for "public backlog" (in quotes), you'll find other examples.

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Structured Approach to Event Blogging

I like the “linkable assets model” in this SEJ post: http://www.searchenginejournal.com/effective-link-building-using-event-blogging/34104/

It’s a nice, structured way to think about how to get inbound links for your event blog (if you’re an event blogger and care about that kind of thing)  🙂