This page explains how this site analyzes data. As a result, it is probably the least interesting page on this site for most people. If you are willing to accept that each episode has the point total that it has, then you might want to go elsewhere.
The webmaster started by obtaining lists through a thorough search of the web for lists of best, worst, favorite, top, greatest etc. episodes. Lists were included if they contained at least ten different episodes and considered at least 122 episodes. The list below describes how the points for each episode were determined. If you are confused, an example is provided below the list.
Suppose that on May 19, 2003, a person (we will call her "Tara Rosenberg") were to present her best and worst episodes as follows:
Honorable Mention (in chronological order):
"Graduation Day, Part 2"
"New Moon Rising"
"Fool for Love"
"Bargaining, Part 1"
"Bargaining, Part 2"
Worst Episodes (in chronological order):
"I Robot... You Jane"
"Some Assembly Required"
"Dead Man's Party"
"Beauty & the Beasts"
"The Weight of the World"
"As You Were"
"The Killer in Me" (least favorite)
"Once More, with Feeling" would be ranked as #1, "Restless" would be ranked as #2, and so on through #7, "Conversations with Dead People." However, Tara seemed to have forgotten that "Becoming" is really two episodes: "Becoming, Pt. 1" and "Becoming, Pt. 2." This means that they take up both the #8 spot and the #9 spot. They are assigned the average of the two and are both put in the #8.5 spot. This means that "Family" is really the #10 episode and "Selfless" is the #11 episode and so on through "Storyteller" at #21.
The honorable mention episodes are not in order of quality, so they are treated as being tied. They take up the #22-#31 spots. They would all be treated as being in the #26.5 spot, the average of the ten spots.
"The Killer in Me" would fall in last place. However, the list was made before "Chosen" aired publicly in the United States (or anywhere else for that matter), so only 143 episodes were considered for this list. Therefore, "The Killer in Me" gets the #143 spot. The other nine episodes are not in order of quality, so they would be considered to be tied. They would take up the #134-#142 spots. The average is 138, so all are treated as being the #138 episode.
Other than the unaired "Chosen", there are 102 episodes that were not mentioned. There is no evidence that Tara has any preference between them, so they are treated as if they are all tied. They would fill the #32-#133 spots, so they all get the #82.5 spot, the average of all those spots.
We do not know where Tara would rank "Chosen" because she had not even seen it when she made the list. It might displace "Once More, with Feeling" for first place or "The Killer in Me" for last place. It might fall on the favorite episode list, the worst episode list, or with the other 102 unmentioned episodes. To account for the probability that "Chosen" would be ranked higher than any given episode, the rank for each episode would be multiplied by approximately 1.007 [(144+1)/(143+1) = 145/144 = 1.007].
Once Tara's list and the lists of a bit under 3,400 of her fellow Buffy fans go through this procedure, the average rank for each episode is calculated and then subtracted from 145 to get the point total for the episode. For example, the average rank for "Once More, with Feeling" is 23.50. This average is subtracted from 145 to get 121.50 points for "Once More, with Feeling." This makes all results look simpler; the more points that an episode has, the better it is.