The aim of a back translation is to find out if the translation is grammatically correct, the meaning clear, the correct message conveyed, with no omissions or additions. In principle, a back translation will allow a non-native speaker of the target language to check that the translation correctly conveys the meaning of the source text.
STEP 1. The back translation is performed by an independent translator with no access to the original source text, but who is made aware that they are working on a back translation.
STEP 2. Once the back translation task has been completed, a reviewer compares both versions and marks up all discrepancies, places where the meaning may be unclear or ambiguous, and any potential issue.
STEP 3. Because the back translation is never be 100% exactly the same as the original source text and due to the nuances in languages, in most cases the reviewer will need to clarify with the translators. However, it is never clear whether the problems stem from the original translation or from the back translation. The reviewer usually sends his report first to the original translator, who may or may not agree to amend his translation. If the original translator insists that he is correct, the back translator is consulted, until eventually all issues have been sorted out and the final text satisfies all. This is sometimes called reconciliation.
STEP 4. The final approved translation is sent to the client, along with the annotated/commented back translations, outlining all discrepancies and how they have been addressed.
The process of back translating is very common amongst pharmaceutical companies, medical device companies, clinical research organisations. For those organisations and institutions, having a back translation to verify content is a legal and regulatory requirement. Most IRBs (Institutional Review Boards) and Ethics committees require that certificates of accuracy and back-translations are submitted with all translated materials. In such high risk situations, back translations are well worth the investment, adding an extra quality assurance step to the translation process. Language Professionals regularly produces back translations for client in the medical and pharmaceutical fields.
On the other hand, back translation is a highly time-consuming and expensive process. Because the main aim of back-translation is to ensure accuracy, it gives no real indication of the actual quality of the original translation. In fact, a bad or literal translation will often produce an excellent back translation!
• Apparent discrepancies in using singular or plural (there are no dedicated plural forms as such in e.g. Vietnamese or Chinese)
• Apparent discrepancies in using tenses (again, tenses are often not marked in other languages the way they are in English)
• Apparent discrepancies in using “and”/”or”
• Addition of some words to make the back translation flow better, but that do not exist in the original translation or the original source text, such as “any”, “some”, etc…
Many such apparent linguistic discrepancies are often incomprehensible and alarming to clients, as they signal non-conformity in translation when in fact this is not the case.
Given the amount of time, cost (back translation plus reviewing time), and also potential for incorrectly identifying issues of back translations, other forms of checking are usually preferred to back translation, unless in the specific context of medical, legal or technical translations.
For example, NSW Multicultural Health does not recommend back translation, but favours independent checking instead. Their rationale is explained here: http://www.mhcs.health.nsw.gov.au/services/translation/pdf/guidelinesforcheckingofhealthmedicaltranslations.pdf