By the way, the Best Case/Worst Case project, enjoyable and rewarding as it has been, put me a little behind the curve on some of the preparation for the full swing of the season. I don't want to get too far behind on the daily posts, so some of this stuff is somewhat subject to change and/or not quite as polished as I would like just yet. I'll get into some of that in the number descriptions. Here goes!
Viewers - From Nielsen. The total number of viewers (age 2+, in millions) that watched the program. Though this number has a dubious correlation with renewability and advertising rates, it is the most easily accessible TV ratings number.
A18-49 - From Nielsen. Adults 18-49 rating. Percentage of US TV-owning adults 18-49 watching the program. This is the publicly available TV ratings currency that correlates best with renewals and ad rates, so I talk almost exclusively in 18-49 terms. For more on why I use this and not total viewers, I recommend the Intro to Nielsen Ratings and the Peetooplus project.
Last - Calculation. A18-49 percent difference from previous episode. This has become sort of the standard-issue number in the great race to make daily ratings interesting. I'm not someone who obsesses over these for every single show every single week, because I think most individual fluctuations are meaningless and boring, and quite a few are misleading, but it's still a pretty reliable go-to way of explaining what happened last night.
LeLa - Calculation. A18-49 percent difference between the show's lead-in and its lead-in for the previous episode. Typically, if the listings are the same as last week, you can just look to the "Last" of the program above it to get this number. This number is at its most useful when a show has a drastic change in lead-in. It's meant to be used in tandem with "Last" as a possible explanation for week-to-week fluctuations. Since I don't have half-hour breakdowns till next week, LeLa compares full program ratings; so if last week's lead-in had a 2.0 average but a 2.5 in the last half-hour, the LeLa compares to the 2.0. (The last half-hour numbers can be seen later in the SpotVault.)
Rank - Calculation. The A18-49 rating's rank among the show's episodes that have aired so far this season. I kind of avoided getting too heavily into the "season/series low" stuff late last season because I just don't find it all that newsworthy when it's happening to everyone. Still, I think I need some number that refers back to the rest of the season beyond last week, and especially early in the season I prefer this to the "Avg" number used last year.
Side note for the opening few weeks: I start a new sheet for each new season, so the late-summer shows that the 2012-13 sheet picks up "in progress" have issues referring back to all the numbers from early in the summer on the previous sheet. I'm going to try to stay on top of these Rank numbers manually for the next couple weeks, but I may mess up on occasion. Let me know if any of them look funky.
y2y - Calculation. The show's A18-49 rating compared to its A18-49 rating a year ago. This is roughly the "SHOW" portion of my daily "Demos Year-to-Year" posts of past seasons, although the formula is more complicated. I have always been hesitant to have the year-to-year numbers in the mix all season because I don't think they're all that helpful during non-sweeps periods. But it's also been kind of awkward setting them aside in separate posts. So maybe I just won't refer to them during non-sweeps periods!
Anyway, the algorithm for "y2y" is kind of complicated, and this is one of the things I'm still working on. Here is the process the y2y number goes through for now:
1) Premieres and finales are always compared against premieres and finales, regardless of dates.
2) During non-sweeps periods, ratings are compared against the same Monday thru Sunday week last year. The traditional premiere weeks (9/19-9/25/11 and 9/24-9/30/12) are about a full week apart this year on the calendar, but both are labeled as "Week One" in this comparison, with all other dates assigned a week label revolving around that.
3) During sweeps periods, ratings are compared against the same Thursday thru Wednesday sweeps week last year. This is the number used in the "Demos Year-to-Year" posts last year.
4) Failing to find a comparison in any of those three steps results in "n/a."
I might tweak this a little more. I would like to try to weed out premiere-vs.-non-premiere and finale-vs.-non-finale comparisons. But I'm not sure if I will get that portion done.
TLa - Calculation. The show's A18-49 rating compared to the network's rating in the timeslot one week ago. This number is not useful all that often in terms of evaluating the show itself. I will probably make the most use of it to note changes in competition for other shows. I thought about just trying to resurrect the "CoLa" (last week's competition) number I used when I first started these posts, but the problem is I can't make that number accurate without having this week's half-hour breakdowns. So as with LeLa, the best bet is to consult the SpotVault for more accurate competition numbers.
Ty2y - Calculation. The show's A18-49 rating compared to the network's rating in the timeslot one year ago. This is the "SLOT" portion of my daily "Demos Year-to-Year" posts of past seasons. Again, this is not that useful during non-sweeps periods when the comparisons are largely original-vs.-repeat, so I'll try to point to it when I think it's at its most relevant.
A note on the two timeslot numbers: Even in scenarios where it's the same show in the timeslot both times, these comparisons will sometimes look a little different from the "Last" and "y2y" since the timeslot numbers compare vs. my half-hour breakdowns. That means it'll compare vs. an average of half-hour numbers that round to one decimal point rather than a full program rating that rounds to one decimal point. For example, a one-hour show could have a 2.5 average and 2.6 -> 2.5 half-hours, meaning it's treated as a 2.5 in the "Last" comparison and a 2.55 in the "TLa" comparison. I came up with a fix for this in the Demos Year-to-Year posts to try to minimize confusion, though I think it had a couple bugs, so I'll work on a fixed version of that if I have time.
True2 - Calculation. The second edition of True Strength, a metric that adjusts the A18-49 rating for overall viewing levels, competition and lead-in. Trying to explain it any more than that is probably hopeless without writing pages upon pages, so I'll just point you to this summer's wrap-up.
As last year, all Monday to Friday True2 numbers in daily posts (and sometimes Sunday) are PRELIMINARY True2. These are recalculated next week when I get half-hour info, and the FINAL versions go up exclusively in the SpotVault.