Credibility

Credibility as a Form of Trustworthiness

There is considerable divergence in researchers' approaches to defining and assessing trustworthiness and in the strategies they advocate to increase the trustworthiness of their research. The labels internal validity, external validity, reliability, and objectivity have established themselves as the standards for trustworthiness in quantitative research. For qualitative research, these terms may not be perceived as relevant or applicable, leading qualitative researchers to (a) redefine the terms in the context of qualitative research; (b) adopt alternative terms that more closely fit qualitative research, usually describing their new terms in relation to the standard terms; or (c) reconceptualize notions of trustworthiness by building arguments about the ways that their reconceptualized approach is more faithful to the underlying philosophy and commitments of their particular form of qualitative research than the standard quantitative concepts and terminology.

The notion of credibility is most often associated with the framework presented by Yvonna Lincoln and Egon Guba. They outlined four key questions that relate to the trustworthiness of research findings and provided divergent sets of terminology for quantitative and qualitative research approaches:

• Are the findings “true” for the participants and the context? This question refers to “truth value,” which is an issue of internal validity or credibility, that is, the degree to which the researcher appropriately identifies or measures the presence or absence of central constructs or relationships among those constructs.
• Are the findings applicable in other contexts or with other people? Judgments about applicability are typically discussed under the label external validity, which considers whether the findings can be generalized or transferred to another setting.
• Would the findings be similar if the research were repeated with the same or similar participants in the same or similar context? This is a question of consistency, which may be considered under the labels reliability or dependability.
• How much have the researcher's biases and perspectives influenced the findings? This idea of neutrality may be discussed as the elusive concept of objectivity or as the less stringent term, confirmability.

As indicated, the first of these four criteria involves credibility or internal validity. This criterion must be considered in relation to the other notions in order to assess the overall trustworthiness of the research data and the resulting reports.

Credibility, Internal Validity, and Reality

Credibility and internal validity are two ways of thinking about the extent to which a research account is truthful. Researchers who perceive the existence of an external reality that can be measured or approximated through research data tend to commit themselves to goals of demonstrating that their measurements truly reflect research constructs as they exist in the external world. These researchers tend to adopt the language of internal validity to discuss the resulting truthfulness of their research accounts. For these researchers, there are various theoretical approaches, some with accompanying statistical measures, to assess the match between their research data and some external reality.

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