AKB48 Janken Tournament 2014 – Conspiracy theory disproved?

I just finished watching the latest AKB rock-paper-scissors tournament and want to write my thoughts on it. Statistically, I find it very fascinating, especially in conjunction with the results from last year.

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In rock-paper-scissors tournament, matagame really matters

It pays to understand the sentiment going into rock-paper-scissors tournament. Last year, Matsui Jurina famously won by playing only paper. So what happened this year? Girls came out playing papers at a ridiculous 46% of the times in round 1 and 2.  The rate went down massively in later rounds when in round 5-7, it is only played 21% of the times, but at overall rate of 42% throughout the tournament, it seems that most girls took to heart of Jurina’s strategy and played paper more than normal.

In contrast, in the last tournament, rock is played 41% of the times, which made Jurina’s paper strategy so effective. She obviously did not fare so well this time, losing to paper in the third round

Thus, my lesson is that knowing the psyche of the current tournament is much more important. If someone manages to guess this Jurina-led trend and keep playing scissors, they would have a much better chance of winning

Winner’s strategy is much less clear this time around and the conspiracy theory is a but thin

For the eventual winner Watanabe MiyukiThere seems to be a lot of conspiracy theory around that came when a popular girl won the tournament. I looked at the results and it is very unclear on how the event would have been rigged since she seems to have no seeable patterns of plays. Last year she lost in her only appearance in the second round playing scissors. This year, here is her play pattern

Round 2: Paper -> Scissors

Round 3: Rock

Round 4: Paper -> Scissors

Round 5: Rock

Round 6: Scissors -> Rock

Round 7: Rock -> Rock

I personally do not see any pattern to her plays, as she threw rock three times, paper twice and scissors one first time round in each round and she went either with stronger or equal hands in the second time (I read from HunterxHunter that normal human behavior in rock-paper-scissors is to throw stronger hand to your previous hand to signify strength. So if you threw rock in your first hand, you’re more likely to throw paper in your second, so Milky passed this test).

Now let’s look at her opponent to see if there is any pattern whatsoever. I will look from round three as there should be enough hands to look through,

Third round opponent: Ota Nao

• Round 1: Scissors
• Round 2: Paper
• Round 3: Scissors

Fourth Round opponent: Uchida Mayumi

• Round 1: Scissors -> Scissors
• Round 2: Rock
• Round 3: Scissors -> Scissors
• Round 4: Paper -> Paper

Fifth Round opponent: Kotani Riho

• Round 1: Rock
• Round 2: Scissors
• Round 3: Paper
• Round 4: Paper -> Scissors -> Scissors
• Round 5: Scissors -> Scissors

Sixth Round opponent: Iwatate Saho

• Round 1: Scissors
• Round 2: Paper
• Round 3: Scissors -> Rock
• Round 4: Rock
• Round 5: Rock -> Scissors -> Rock
• Semi Final: Scissors -> Rock -> Scissors

Final opponent: Kojima Haruna

• Round 1: Rock
• Round 2: Paper -> Rock
• Round 3: Scissors -> Rock
• Round 4: Scissors
• Round 5: Paper -> Rock -> Rock
• Semi Final: Scissors
• Final: Rock -> Scissors

This looks random enough to me, with all girls throwing all sorts of hands before and during the matches against her. Looking at the people who got to the last 16, it also looks random with a mixture of popular, past-popular and up and coming girls. Can we hypothesize that maybe the popular girls just wants it more or have more lucky aura that have gotten them this far? If we can say anything about the conspiracy theory, Milky actually got first round bye two years in a row so either she’s lucky or someone wanted to make it easier for her to win.

I also wanted to do a more in-depth statistical analysis on the likelihood of that happening

I’m personally not on the conspiracy theory camp when it comes to the tournament but I was just watching the Sugar Rush PV and realized that the last three winners (Shinoda, Shimazaki and Matsui) were all in the 10-member lineup. The chance of that happening is about 0.12%. I can see how conspiracy theory came about with the management seeing that the first janken that Uchida won did not sell well (-300k less sales that the previous single) and they needed to fix the result so a more popular member got it and voila, the sales number remained relatively high. Then again, I’m talking from the likelihood perspective and has no other proof to back this hypothesis up.

NMB48 blew the competition away

• Against members from other groups, NMB members won on 68% of the times  (W-L = 19-9)
• HKT is the least lucky winning 5 losing 7
• There is only 2 non-AKB same-group duels, withNMB’s  Watanabe Miyuki beating Kotani Riho in the 4^th round and HKT’s Tomonaga Mio beating Matsuoka Natsumi in the first round

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Other statistics for this tournament:

• Longest match: 5 between Kodama Haruka and Ishikawa Manami, in which Haruppi’s persistence paid out after throwing 5 papers in a row!
• Most number of matches: 12 by Kojima Haruna
• Most number of papers played, aka the Jurina award: 9 thrown by Arai Yuki. In fact, that is the only hands she played the whole tournament, even more than the 8 Jurina threw last year. In fact she’s the only person with more than 3 hands played who went with only one hand type
• Most share of rock hands: 3 out of 3 by Maeda Ami, including the last one that she ‘changed’ to scissors. Poor girl
• Most share of scissors hands: 3 out of 3 by Miyawaki Sakura

Some interesting stats that I think still holds:

• Sashihara is probably the only 6-time losers in the whole Janken tournament! She participated in all 5 (including prelim, plus the extra prelim in the 3rd one)
• When Miyazaki Miho and Iwasa Misaki won, we lose the chance of seeing someone lost 5 times in 5 tournaments
• Talking about losing streak in the main tournament, Katayama Haruka still holds it at 4, losing her only appreances in the first 4
• Uchida Mayumi is still amazing in odd-number tournament, coming 1^st in 01, semi-final in 03 and top 16 in 05, while losing in the first rounds in 02 and 04

My thoughts while watching

• What happened to Maeda Ami? It did look like she was going to throw scissors… So sad. Would have loved to see her do well, especially with her awesome Kiki costumeJ
• There were 4 scissors win in a row in block E. Like I said above, it did pay to play scissors early in this tournament
• That does not work of course if you already told people what you are going to play (see Mayuyu)
• After the 4^th round, there were only one person left winning on the left hand side of the screen and 7 on the right! That has a 0.8% chance of happening

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At the end of it, I still enjoy this janken tournament and do look forward to them doing it again next year. If anything, it will be fun to get another year of rock-scissors-paper data!

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