Quality of translation may be expressed by the following equation:
E[q] = α + β(standard difficulty of text) + ε
where E[q] is the expected quality of translation, α is the ex-ante alpha, β is the difficulty of a text, and ε is an idiosyncratic factor.
Ex-ante alpha is generated by careful selection of words and skill of the translator, not by luck, indicating that translations consistently offer superior quality.
β is the level of difficulty in understanding the text, which is 1 if the text is of standard difficulty. Examples of texts of standard difficulty include articles of newspapers and magazines written for the general public. β rises as a text requires special knowledge and experience, posing a challenge to any translator.
ε is an unpredictable factor, caused by a one-time happening or luck that affects the quality of translation. A telltale example is that in late October of 2015, the website of Japan's Health, Labor and Welfare Ministry became inaccessible due to an alleged cyberattack, making it impossible for translators to check the terminology and system of Japanese pension.