3019: Advent Calendar Advent Calendar

2024-12-03T00:41:04Z

172.70.162.173: /* Explanation */ "1st" would be 24 days until, "24th" is 1 day until, "25th" would be zero, leading to 300 sub-items (and either 24 or 25 sub-advents, themselves, depending upon the meta-advent including the 25th)

{{comic
| number = 3019
| date = December 2, 2024
| title = Advent Calendar Advent Calendar
| image = advent_calendar_advent_calendar_2x.png
| imagesize = 482x324px
| noexpand = true
| titletext = The growth rate of items per day may may seem absurd, but it's actually much less than the acceleration in the 12 Days of Christmas song.
}}

==Explanation==
{{incomplete|Created by 4 ENVELOPE BACKS 3 NERDS A-EDITING, 2 TURTLE BOTS, AND A FUNNY NEW XKCD - Please change this comment when editing this page. Do NOT delete this tag too soon.}}
Advent calendars are a form of countdown to Christmas consisting of a card or structure with one closed "window"/opening for each day. Every day, another "window" is opened (e.g. a cardboard flap is opened along perforations), revealing a small present (traditionally, just a thematic picture or chocolate). While the religious season of {{w|Advent}} traditionally begins four Sundays before Christmas, most Advent calendars begin on December 1st for simplicity. Notice that in 2024, when this comic was published, the Advent season coincidentally starts on December 1st.

In this comic, Randall has devised an Advent calendar that contains multiple smaller Advent calendars, each of which contains the same number of items as there are days left until (and ''including'') Christmas Day. By the time he reaches Christmas, he will have 325 different items, or 350 if counting the sub-calendars. The calendar is shown as it might be on December 2nd, the date of publication of this strip. The "window" for December 1st, in the upper left, has 25 sub-windows, of which 2 are open. (One was opened on December 1st and the other on the 2nd.) The "window" for December 2nd, 5th from the left in the bottom row, has 24 sub-windows, of which 1 is open.

It is not clear what is inside each sub-calendar. The usual filling would be chocolate, however it could also be possible that the advent calender advent calendars had even more advent calendars within.

The title text refers to {{w|The_Twelve_Days_of_Christmas_(song)|The Twelve Days of Christmas}}, a traditional Christmas carol in which the singer receives many gifts from their paramour for each day of the Twelve Days of Christmas. On day one, they receive one gift, and on day ''n'', they receive again all the gifts they received on day ''n-1'', plus ''n'' copies of a new gift. The exact gifts given each day vary by version of the song, but the result is that the number of gifts given each day follows the {{w|triangular number}} sequence ''(n+1)n/2'': 1, 3, 6, etc., receiving 78 gifts on day 12, for a total of 364 gifts. For the Advent calendar Advent calendar, each day a number of items equal to the number of days left until christmas are added. Once we reach the 8th day of Christmas, the song’s growth rate exceeds the calendar’s. There are 364 items total in the 12 Days of Christmas, more than the 325 in these nested calendars.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
:[On a grey board, there are 23 Advent calendars behind large "windows", numbered from 3 to 25, plus two open calendars with their covers torn off.]
:[Each calendar numbered ''n'' has 26−''n'' squares in it.]
:[One open calendar has 25 squares, 2 of which are black. The other open calendar has 24 squares, one of which is black.]

:[Caption below the panel:]
:I like Advent calendars, so I got an Advent calendar that gives me a new one every day until Christmas.

{{comic discussion}}

[[Category:Christmas]]
[[Category:Calendar]]
[[Category:Songs]]

Talk:2533: Slope Hypothesis Testing

2021-10-27T11:50:44Z

172.70.162.173:

In the line "Randall has repeatedly made comics about this hopeful error", should specific examples be provided? I know /882 is one, but I'm blanking on any others. [[Special:Contributions/172.68.132.114|172.68.132.114]] 10:21, 26 October 2021 (UTC)
:Definitely, otherwise it would not be very useful. --[[Special:Contributions/162.158.203.54|162.158.203.54]] 13:10, 26 October 2021 (UTC)
:hi, I added the line. <thinking-out-loud removed in copyediting>. I think there was one where article titles that blatantly used poor statistical techniques were listed, not sure. [[Special:Contributions/172.70.114.3|172.70.114.3]] 14:40, 26 October 2021 (UTC)
I love it. [[User:Fwacer|Fwacer]] ([[User talk:Fwacer|talk]]) 02:52, 26 October 2021 (UTC)

I imagine that the problem here is that the errors are not independent. I can't find anything else wrong with this, but I feel like there's something obvious I'm not seeing. They might revoke my statistics degree if I miss something big here, hehe.--[[User:Troy0|Troy0]] ([[User talk:Troy0|talk]]) 03:06, 26 October 2021 (UTC)
:The scores are clearly the one score they originally (sometime prior to the expanded test) received. Either that or multiple tests with the same exam questions without having given them enough feedback to change their answer-scheme at all. The volumes are probably a "good go at screaming" on demand, belying any obvious "test result -> thus intensity of scream" (what might be expected if the scream(s) of shock/joy/frustration were recorded immediately upon hearing a score).
:What they have here is a 1D distribution of scream-ability/tendency (which was originally a single datum), arbitrarily set against test scores. (Could as easily have been against shoe-size, father's income-before-tax, a single dice-roll, etc.)
::I initially assumed that the participants are screaming in response to learning their scores, so the relationship is not arbitrary -- the students with good scores sceam loudly with joy. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 14:45, 26 October 2021 (UTC)
:::Perhaps it was that (except the screaming volume is clearly confounded by other factors, such as how loudly they normally scream) but asking them to "scream again" seems to show far more personal correlation than emotional attachment, for they are the same people but time has passed to reduce the spontenity of the response and their newer submissions are ''at best'' "try to scream like you did when you heard your score the first time". Which is problematic and not really a valid new response to add to the list. At best, it's a test of replay consistency (now unlinked from the original feeling). [[Special:Contributions/172.70.85.185|172.70.85.185]] 15:57, 26 October 2021 (UTC)
:Whether there ''was'' an original theory that grades correlated with intensity of vocalisation is perhaps a valid speculation, but clearly the design of the test is wrong. Too few datum points, in the first instance, and the wrong way to increase them when they find out their original failing.
: The true solution is to recruit more subject. (And justify properly if it's intensity of spontaneous result-prompted evocations or merely general ability to be loud that is the quality the wish to measure. Either could be valid, but it's not obvious that the latter is indeed the one that they meant to measure.) [[Special:Contributions/141.101.77.54|141.101.77.54]] 04:21, 26 October 2021 (UTC)
: It's pretty straightforward. This is a simple linear regression, Y = α + βX + ε, where α and β are parameters and ε is a random variable (the error term). Their point estimations for α and β are correct. But their confidence intervals (and thus p-values) are wrong, because they are based on a false assumption. They constructed their intervals assuming ε was normally distributed, which it clearly is not. ε will always be approximately normally distributed if the central limit theorem applies, but it does not apply here. The central limit theorem requires that the samples be independent and identically distributed. Here, they are identically distributed, but they are not remotely independent. After all, the same people were selected over and over again. Therefore ε will probably not be randomly distributed (it isn't even close), and the confidence intervals (and so p-values) are wrong. [[Special:Contributions/172.70.178.47|172.70.178.47]] 09:10, 26 October 2021 (UTC)
:: You seem to be the only person so far who's learned in academia why this is wrong. Is the current state of the article correct? [[Special:Contributions/172.70.114.3|172.70.114.3]] 14:31, 26 October 2021 (UTC)
: The scientific error isn't quite what people are saying it is. The issue here is not "reusing a single test score" or an issue with non-normality of errors, the issue is that the data are *nested* within participants and that isn't being accounted for. There are fairly standard ways of managing this, at least in the social science literature (and these ways are statistically valid), most commonly the use of multilevel modeling (also known as hierarchical linear modeling). This accounts for the correlated nature of the errors. Now, even using the right method they're not going to attain statistical significance, but at least they aren't making a statistical mistake.

I don't think the title text speakers are unidentified, I'm pretty sure it's a direct continuation of the dialogue in the last panel. [[User:Esogalt|Esogalt]] ([[User talk:Esogalt|talk]]) 04:11, 26 October 2021 (UTC)
:I agree. the second speaker starts to say "I said, are you sure--", this is the start of Cueball's last line. I think this is intended to be Cueball and Megan trying to talk about the results while the students are still screaming. [[User:TomW1605|TomW1605]] ([[User talk:TomW1605|talk]]) 06:45, 26 October 2021 (UTC)
::It could also be the case that their hypothesis was true and they failed so badly at statistics, that their voices are inaudible now.
:::Because, since they didn't write that test, their score is zero. [[Special:Contributions/108.162.241.143|108.162.241.143]] 14:29, 26 October 2021 (UTC)

Is there a polynomial that better fits this data? [[Special:Contributions/108.162.241.143|108.162.241.143]] 14:29, 26 October 2021 (UTC)
:Given three points, there's a ''circle'' that exactly fits them... ;) [[Special:Contributions/172.70.85.185|172.70.85.185]] 15:57, 26 October 2021 (UTC)
:Also, infinite number of polynomials which fits this data exactly. -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 23:06, 26 October 2021 (UTC)
::But ''exactly one'' circle (assuming all mutually different, and not already upon a line), in an {{w|Circumscribed_circle#Triangles|elegantly obvious}} manner. Therefore clearly the more individually significant statistical match for three datum points. :P [[Special:Contributions/172.70.162.173|172.70.162.173]] 11:50, 27 October 2021 (UTC)

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3019: Advent Calendar Advent Calendar

Talk:2533: Slope Hypothesis Testing