Grand Blue – Deviation Value

Context: There was a mathematical term used in the manga that is only really used in Japan. This blog post is mainly to explain what it is. The line is located on the cover page of Chapter 37 (above the title). We used Love Quotient in the end instead of Deviation Value, but I think the concept is interesting still.

Deviation Value:

Deviation Value is a mathematical concept used in Japan, primarily by the education/school system. It follows the same statistical concepts of z-scores that we use in the western world, but has a slightly more specialized formula. There’s going to be a lot of math, so if you’re only interested in translation-related stuff skip to the end. TL;DR: Deviation Value is Z-score with mean 50 and standard deviation 10.

The formula is as follows:


Source: Wikipedia Japan

The formula we use in the rest of the world to calculate Z-score is

Standard Score Calculation

(taken from

Described literally, a Z-score is the number of standard deviations an individual value differs from the mean. For example, a Z-value of 0.66 would be described as “0.66 standard deviations to the right of the mean”. Z-values typically vary from -4 to 4, since 99% of values fall within this range. The score is used to identify where an individual value falls within a sample, or to find the interval where a certain percentage of the sample falls (for example, top 10%). These percentage values are generally found through consulting a z-score table such as this.

Image result for z-score table

As you see, this table only goes up to 3.49 since that covers most values already.

It appears that Deviation Value is essentially the same thing as a z-score, except standardized to be centered around the value 50, and one standard deviation = 10 DeviationValue. Essentially, to convert from Deviation Value to Z-score, we use the formula

Z-score = (DeviationValue-50)/10

I’m not entirely sure why the Japanese use this system. Maybe it’s easier to think with factors of tens in Japanese, rather than having decimal numbers.

Moving on to the translation, the phrase we had to translate was 恋愛偏差値25野郎どもの現代神話!. There are a lot of interesting things going on this phrase, mainly in word choice.


Literally means “love”, however it is being used as the “field/subject/population” in which these idiots fall 2.5 standard deviations below the average.


Converting a Deviation Value of 25 into Z-score:

Z-score = (25-50)/10 = -2.5 -> bottom 0.0062%

Localization would use z-score. Lit. translation would use deviation value. Liberal would maybe try using bottom 0.0062%.


This is kind of a generic insult/moniker. Due to the series, I think “idiots” is appropriate, although maybe a bit liberal.


It’s a bit clunky, but I want to keep the exact phrasing of “modern-day legend”. I like respecting the author’s word choice.

Putting it all together… I tend to pick and choose from different styles to get a line which sounds nice in my head.

A modern-day legend of idiots with a Z-score of -2.5 in love!

This is what I first came up with, although I’m a bit uncomfortable because of how the phrasing ‘in love’ works. This can be parsed as “A modern day legend of idiots with a Z-score of -2.5, now falling in love!”, when the actual meaning of the line is that these idiots are terrible at love. (The wording of love is awkward in general to be honest… ugh). This is when I learned that there was a T.V show called 恋愛偏差値, or “Love Quotient” in english. I don’t believe that the line is an actual reference to this show(since I believe it is a statistics joke), but we can borrow that phrasing since it isn’t half bad! (People can come read this long ass translation note if they care about the finer details).

“A modern day legends of idiots with a love quotient of 25”!

I really want to use Z-score since it adds to the theme of the chapter, but it’s a bit difficult to fit into a nice-sounding line in english.

Bonus: Measurement Error.

I wanted to go with Systematic Error, which is a more precise term for this kind of measurement error. Kenji describes it in the script as “the error that occurs when measuring values that are smaller than the gradient markings on the measurement device”. Our PR viewed this as a resolution error, while I view it from the point of view of “human error”. I believe the difference between analog and digital measuring devices is the removal of human measurement from the equation that makes the digital measurement more accurate. Both of these kinds of errors exist though, so it is essentially an argument about nothing in the end. In the end PR wanted measurement error since it makes more sense to the layman. I like Systematic Error a lot more since I believe it would lend to the tone of the chapter more, but it’s more or less the same.

Although short, this is one of the better chapters in my opinion.

9 thoughts on “Grand Blue – Deviation Value

  1. Not related to the topic, i was wondering if the chapter for this month is delayed or there is no monthly chapter for this month.

  2. 偏差値 isn’t Z-score. It’s T-score as someone else mentioned. 偏差値 or hensachi is a very common term in Japan unlike in America. It’s used to gauge students’ relative academic ability somewhat like SAT scores in America. It’s also understood that the typical score range is from 25 to 75 and 75 being the highest. So when someone says 偏差値25, it signifies the bottom of a ranking or complete lack of abilities. Hence 恋愛偏差25野郎ども means dudes with the total lack of experience and prospects in romantic relationships.
    If you want to preserve the nerdy/technical feel of the original expression, I would go for something like “below 1 percentile ranking ” because it still preserves the nerdiness while conveying the meaning to most people (and also technically correct).
    So I would say “dudes below 1 percentile ranking in romantic relationships.”

  3. I’m aware of T-distributions, but I wasn’t aware T-score was a thing. It is essentially what I coined the term “Deviation Value”. I wonder how widely used it is, since I haven’t actually encountered it until now (definitely not used as much as it is in Japan). It is calculated based off the Z-score (which was the purpose of this post, and I believe Z-score to be a much more familiar term for most people).

    I could’ve used a percentile ranking (which I mentioned in the post) as a liberal translation, but it felt clunky even then and I wanted to keep the technical term used. I kind of like love quotient, although T-score could definitely be used since apparently we have the mathematical concept in english as well.

  4. 翻訳する側の人間として、ただ単に正確に直訳すれば良いと言うのはどうかと思うけど。アメリカで偏差値25/T-score of 25 なんて言っても誰もその値の意味もわからないし、ましてや恋愛偏差値25の意図する所なんて全く伝わらない。T-scoreが英語にもある概念だからと言って英語圏でも同じレベルで一般に浸透してるわけじゃないから。

  5. あれはあくまでもスタイルの話になる。英語では、「上位1%」とかのようなの言い方なら、多くの人が分かる。でも、翻訳者の仕事はただ『わかりやすい」ように解釈するのではないと思う。英語に書き直す必要がある場合は確かにあるが、できるだけ日本語で使った単語を保存したい。

    「 恋愛偏差値25野郎どもの現代神話!」は読者たちにどんな感情をさせる?多分読むとピンと分かって、微笑するでしょう。それなら「A modern day legend of idiots in the bottom 1% of the mating pool]などの翻訳は一番近い。この翻訳は多分リリースしてた翻訳よりいいかもしれない。

    リリースしてた時の狙いは「数学」のテーマに合わせることだった。上の翻訳は確かに感情的にぴったりですが、数学のテーマにあまり繋がっていない。テーマに合わせるために、もう少し数学っぽいな翻訳を選択しました。これは確かに原作から離れる、そして多くの人にあまり通じないけど、正しい数学単語を使ってたら、数学を分かる人と深い繋がりを生むでしょう。まぁ[love quotient」は正しい単語じゃないからあまり言い訳にならないだけどね。

Leave a Reply

Your email address will not be published. Required fields are marked *