I think there is no formal research about abbreviation of Japanese vocabularies; however some people who are involved into Japanese language education for non-native speakers seem to have tried to explain how Japanese native speakers make abbreviations for Japanese words.
I found some articles:
Please read them for further information.
The following description is merely an explanation from my personal observation so there should be some points to be corrected.
Usually Japanese words are abbreviated into four syllables. If it is impossible to abbreviate into four syllables by some reason, then try three syllables. Finally if it is also impossible to abbreviate into three syllables, then abbreviated it into two syllables.
I listed up some examples below :
Words which are abbreviated into four syllables
- 吉野家{よしのや}の牛丼{ぎゅうどん} → よしぎゅう
- ポケット・モンスター → ポケモン
- 鋼{はがね}の錬金術師{れんきんじゅつし} → ハガレン
- こちら葛飾区{かつしかく} 亀有{かめあり} 公園前{こうえんまえ} 派出所{はしゅつじょ} → こち亀{かめ}
- ベルサイユのバラ → ベルバラ
- 魔法少女{まほうしょうじょ}まどか☆マギカ → まどマギ
- 黒子{くろこ}のバスケ → 黒{くろ}バス
- 魔女{まじょ}の宅急便{たっきゅうびん} → 魔女宅{まじょたく}
- 東京電力{とうきょうでんりょく} → 東電{とうでん}
Words which are abbreviated into three syllables
- アイスコーヒー → アイコ
- コストパフォーマンス → コスパ
- 軍用手袋{ぐんようてぶくろ} → 軍手{ぐんて}
- マクドナルド → マック
Words which are abbreviated into two syllables
- 新世紀{しんせいき}エヴァンゲリオン → エヴァ
- リプライ → リプ
Note that yo:on 拗音{ようおん} ( a kana letter which is followed by a small kana letter such as じゃ/じゅ/じょ) are considered as one syllable.
As you can notice, most words are abbreviated into four syllables. It is unclear even for me when it should be abbreviated into three or two syllables and why. (I am actually a native Tokyo dialect speaker but I also cannot tell why and how).
The way how to decide four, three or two syllables to abbreviate may be out of social coincidental occurrence or it has some benefits when they make rhyming catch phrase etc. which reason is not clearly defined.
For example, マクドナルド(McDonald) could be abbreviated into four; it could be マクドナ, but there is no one to call it like that. In fact, マクドナルド is abbreviated into three in 関西(West Japan) districts as マクド. In Tokyo, it is usually abbreviated as マック.
Generally the words which consist two or more clauses are get abbreviated by taking two syllables from each word's head and bring them into the abbreviated word. For example:
- ポケットモンスター
- ポケット モンスター
- ポケ モン
- ポケモン
There are a lot of exceptions in it: for example, the word サラリーマン has two parts of clauses as サラリー/マン , but it does not come into サラマン or something, it is usually abbreviated as リーマン which forms an irregular abbreviation.
But in most case, I think it is enough to know the way how four syllable abbreviations are achieved.