Four strategies for maintaining content equivalence: advantages and disadvantages
Importing a scale for use in another language or culture often requires considerable effort by researchers to maintain the quality of translation (Brislin 1970, Sechrest & Fay 1972, Wang et al. 2006). Brislin (1970) offered four techniques for maintaining the equivalence between the original and translated measures: (i) back-translation method; (ii) bilingual technique; (iii) committee approach; and (iv) pretest procedure.
Back-translation is a well-known method to maintain equivalence between the original and translated versions (Behling & Law 2000); Brislin's classic back-translation model (1970) is widely used for instrument validation. Brislin recommended an iterative process of repeated independent translation and back-translation by a team of translators. This approach requires several independent bilingual translators (Triandis & Brislin 1984). A bilingual translator blindly translates an instrument from the original language to the target language; a second bilingual translator independently back-translates the instrument from the target language to the original language. Next, the two versions of the instrument (original language and back-translated version) are compared for concept equivalence. When an error is found in the back-translated version, another translator attempts to retranslate the item. This procedure continues until a team of bilingual translators agrees that the two versions of the instruments are identical and have no errors in meaning (Table 1).
The major weakness related to Brislin's classic translation model is that researchers cannot estimate how many independent bilingual translators are needed to get content equivalence between the original and the translated versions; accessibility and availability of qualified bilingual people who have knowledge of the original (source) and target languages, both cultures, and the focal area of the research is a key when using this method. As an alternative, researchers often use a team approach with two independent bilingual translators (Yam et al. 2004, Thato et al. 2005); yet, this method may amplify the problems of the translated measures when the original and target languages have different structures, the original instrument includes metaphorical or emotional terms, and translation is conducted by unqualified bilingual experts (Brislin 1970, Dunnigan et al. 1993, Russell & Sato 1995, Jones et al. 2001).
The use of the bilingual technique requires the administration of the instrument in both the original and target languages to bilingual participants (Brislin 1970). The responses of the participants to the two versions are compared. When researchers identify a different response, they need to consider the potential reasons for this discrepancy. Yet, bilingual participants’ responses may be different from those of monolinguals (target population) because bilingual people are acculturated to their host culture. This acculturation places them in a separate population from the monolingual population (McDermott & Palchanes 1992, Sperber et al. 1994) and enable them to report different responses even though the two versions of the measure (original and target versions) have content equivalence (Lee et al. 2002).
The committee approach uses a group of bilingual experts to translate from the original to the target language (Brislin 1970). This approach provides a clearer version of the translated instrument as one committee member's mistake can be more readily identified by the other committee members (Brislin 1970). This method may be appropriate to use when bilingual translators have a preference for a target language and a limited number of persons are available for the back-translation procedure. However, this method requires more than three bilingual people and the accessibility of bilingual people as translators is a key issue when applying this approach.
The fourth method used for translation is the pretest procedure (Brislin 1970). The pretest refers to a pilot study. This procedure helps researchers identify potential problems when the population, study conditions, and measures that will be used for a larger study are the same as the pilot study. Accurate information about the potential problem regarding equivalence of translated measures can be obtained according to the level of similarities of the study conditions. While the back-translation method has frequently been used to maintain content equivalence in the translated version, there are limitations when using Brislin's classic back-translation model. Suggested remedies include combining translation techniques and modifying Brislin's translation models (Jones et al. 2001).
Jones et al. (2001) introduced a combined translation technique which uses a group approach when applying the back-translation method and bilingual technique. Firstly, two bilingual experts prepare two translated versions of an instrument from the source (original) to the target language. Secondly, each target language version is blindly translated to the source language by two other bilingual people. Thirdly, the four bilingual people have a group discussion to identify any differences between the target and source versions; they come to a consensus regarding these differences and develop a new version of the instrument. Fourthly, the new version is independently back-translated by two more bilingual people. Fifthly, the new back-translated versions are reviewed in the second meeting of the bilingual people. When the bilingual experts identify any differences between the translated version and source version, the fourth and fifth steps are repeated until the bilingual experts reach a consensus agreement. Lastly, the reliability and equivalence of the two versions is tested on a sample of bilingual participants. The combined back-translation technique, nonetheless, has several weaknesses.
The first weakness of Jones’et al. (2001) approach is the availability of bilingual people. In their study, new bilingual translators join their project at each translation and back-translation steps. Thus, if bilingual translators fail to reach agreement with a translated version, two additional bilingual translators are needed to perform the second translation and back-translation. The required number of translators increases as the process is continued; researchers cannot estimate at the outset how many bilingual translators will be required. In addition, a sample of bilingual people is needed to validate the instrument.
The second weakness is the nature of ‘bilingual technique,’ which was explained earlier; acculturation makes bilingual people different from monolingual people. Thus, another approach may be needed to obtain appropriate translated measures.