Was the Instrument Used in the Same Language?

Does Changing the Language Change the Measurement?

A study says it used a well-established instrument. You follow the citation and discover that the supporting evidence concerns the English version, while participants in the current study completed it in Filipino, Spanish, Arabic, Mandarin, or another language.

Perhaps the researchers used an established translation. Perhaps they translated the questionnaire themselves. Perhaps they say only that it was “translated into the local language” and provide no further information.

Translation does not automatically make an instrument invalid. Researchers routinely need instruments in multiple languages. But translating a measurement instrument is not equivalent to translating an ordinary paragraph. The goal is not merely to produce grammatically correct sentences. It is to preserve the construct and the intended meaning of the measurement as far as possible across languages and cultural contexts.

The Language Version Matters

Translation Is Part of the Measurement Process

Language can influence how respondents understand questions, interpret response options, retrieve information from memory, and decide how to answer. If those processes change systematically between language versions, the resulting scores may not be directly comparable even when both questionnaires look superficially similar.

For that reason, language should be treated as a measurement issue rather than a clerical detail.

First, Identify Which Language Version Was Actually Administered

Do not assume that the language of the article is the language of the instrument. An English-language paper may report research conducted with participants who completed measures in another language.

Look in the Methods section, supplementary materials, instrument citation, or study protocol for the language administered. If the study involved multilingual participants, determine whether everyone received the same version or whether several language versions were used.

Then determine whether that exact language version has its own development, adaptation, or measurement evidence.

Translation Is Not Simply Word Substitution

Languages rarely provide perfect one-to-one equivalents for every word, idiom, grammatical structure, or cultural reference. A literal translation can therefore be linguistically faithful while changing the intended meaning of an item.

PROMIS translation standards illustrate the point. Its translation methodology uses an iterative process that includes forward and back-translation, expert review, harmonization across languages, and pretesting through cognitive debriefing. The aim is to preserve meaning and cultural appropriateness rather than demand identical wording across languages.

This does not mean every research instrument must use the PROMIS procedure specifically. It demonstrates why defensible translation typically requires more than asking a bilingual person to convert the text.

Translation and Cultural Adaptation Overlap but Are Not Identical

A sentence can be linguistically accurate yet culturally inappropriate or confusing. References to foods, occupations, family roles, educational systems, healthcare arrangements, units of measurement, or everyday activities may not carry the same meaning across settings.

Cultural adaptation addresses whether the translated content works appropriately within the target context while preserving the construct being measured. Sometimes this requires wording that is not literally identical to the source.

The second is generally more important for measurement. A beautifully literal translation that changes what respondents understand is not much of a methodological victory.

Forward and Back-Translation Can Help, but They Are Not the Whole Story

A common procedure involves translating the original instrument into the target language and then having another translator translate that version back into the source language. Differences can reveal possible problems.

Back-translation can be useful as part of a broader process. It does not prove that target-language respondents understand the new instrument as intended.

This is why rigorous translation approaches may incorporate multiple reviewers, reconciliation or harmonization, and testing with people from the target population. HealthMeasures describes the PROMIS methodology as including forward and back-translation, multiple reviews, harmonization, and cognitive debriefing with target-population participants.

Ask Whether Target-Language Respondents Understand the Items

Cognitive interviewing or cognitive debriefing can help determine how participants interpret translated questions and response options. Researchers may ask participants to explain an item in their own words, describe what they considered when answering, or identify wording they found unclear.

This is particularly relevant to content validity because comprehensibility is one of the dimensions emphasized in COSMIN's framework, alongside relevance and comprehensiveness.

A translation that sounds excellent to experts can still produce unexpected interpretations among the people who actually complete it. Measurement, as usual, has a way of making elegant assumptions meet actual respondents.

Check Whether the Translated Version Retains the Intended Structure

Translation can potentially alter relationships among items. A distinction that is clear in one language may become less pronounced in another. Response categories may also be interpreted differently.

Depending on the instrument and intended use, researchers may therefore examine structural validity, item functioning, or measurement invariance in the translated version.

COSMIN defines cross-cultural validity or measurement invariance in terms of whether the performance of items in a translated or culturally adapted instrument adequately reflects their performance in the original version. Its guidance notes that factor structures can be compared across groups and differential item functioning can be investigated.

Translation Quality and Cross-Language Comparability Are Related but Different Questions

A carefully translated instrument may be entirely suitable for measuring a construct within the target-language population even if direct numerical comparisons with another language group have not yet been established.

Cross-language comparison imposes an additional demand. If researchers conclude that one language group has higher anxiety, satisfaction, or another construct than another, they need confidence that observed score differences are not substantially driven by the language versions functioning differently.

This distinction matters when reading multinational or multilingual research.

Language Is Also a Population Question

Language rarely exists independently of culture, geography, education, and social context. Even the “same” language may have regional variations, different expressions, and different conventions.

Consequently, evidence for a Spanish translation used in one setting, for example, may be informative without automatically resolving every question about its use among all Spanish-speaking populations.

The language question therefore connects naturally with whether the instrument has adequate evidence in a relevant population.

Do Not Assume the Original Instrument's Validation Automatically Transfers

A translated version may preserve the original instrument extremely well. Nevertheless, the evidence supporting the original language should not simply be relabeled as evidence for the translated version.

This is part of the broader reason why using a “validated” instrument does not automatically make every later measurement valid. The exact version administered matters.

If researchers also change items, response options, instructions, or scoring during translation, the issue extends beyond language and becomes a question of whether the instrument was modified from the supported version.

An English Questionnaire Is Translated for a New Study

Common Mistakes About Translated Instruments

Follow the Exact Language Version Used in the Study

When evaluating a study, trace the instrument from its original source to the version participants actually encountered. This often reveals more than simply checking whether the authors cited a validation paper.

This last distinction matters. Poor reporting and poor measurement are not synonymous. If the authors provide too little information, you may be unable to determine whether the translation was rigorous. That uncertainty should remain uncertainty rather than quietly turning into either reassurance or condemnation.

Check the Language Version Before Accepting the Scores

Questions About Instrument Translation and Language

The Version Participants Read Is the Version You Must Evaluate

How to Cite This Guide

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