How does Facebook determine the box of 9 friends on Facebook timeline?

[Josh]

Is it to with how many profile views.

1st Friend: I've seen this friends page a lot. I haven't liked anything, commented on anything, or IM chat this person.
2nd Friend: Used to view this friends profile a lot. Now not at all yet still on the box of 9 friends and second.
3rd Friend: This friends randomly sent a IM chat one day, ever since then, this friend has been third on the box of 9 friends. I haven't seen this persons profile, liked any statuses, or commented on anything of this persons.
4th Friend: Never view this persons profile page (Never communicated on Facebook)
5th Friend: On rare occasions this friend sends me IM chats. I have never seen this friends profile.
6th Friend: Just added this person on Facebook. Only seen this friends profile 3-5 times in total. Not viewed the friends page the whole of today.
7th Friend: Never view this persons profile page. (Never communicated on Facebook)
8th Friend: Just added this person on Facebook. Only viewed this persons profile once.
9th Friend: I have never communicated with this person on Facebook.

What determines the box of 9 friends on Facebook timeline? Is it the number of times the friend has viewed your page.

[PcM]

It's more 8 people that you get in regular contact or whose timeline you've viewed a lot and one random. Remember that other people viewing your timeline won't see the same people you do, just a random selection of of your friends.

[Ding]

dd

[Louise]

A number of factors seem to contribute to the reasons why you will see certain friends photos show up more often in your 9 Friends picture box on your own profile. These factors include:

Interactions on facebook (recently and over time). Recent interactions play a large role, especially if someone has recently viewed your profile page.
Profile views (they’ve viewed your profile and/ or you’ve viewed their profile – Total amount of views when compared to other friends profiles viewed)
Photos that you’ve been tagged in (or have tagged your friends)
Wall posts
Likes
Comments (on your posts or comments you’ve made on your friends wall posts or pictures)
Photos viewed (they’ve viewed your pictures, and/or you’ve viewed theirs)
Online – Friends who are currently Online (or recently been online for Random people that might show up)
Chat – Facebook IM chat messages between each other
Private messages sent between friends
Any “mutual interactions” between yourself and your friends will likely play a bigger role in determining who your “closer” 8 friends may be.
If you’ve added friends to your “Close Friends” group, typically at least 2 of these “Close” friends will be shown in the 9 friends box.