Internal validity is a cornerstone of research quality, helping us assess the trustworthiness of study findings. While the concept is perhaps most commonly discussed in quantitative research, particularly experimental designs focused on cause-and-effect, its underlying principle is also relevant to qualitative inquiry, albeit interpreted through a different lens.
The Standard Definition (Often Applied Quantitatively)
Based on standard definitions, including the one provided, internal validity refers to the degree of confidence that the causal relationship being tested is trustworthy and not influenced by other factors or variables.
This definition highlights:
- Causal Relationships: The focus is on establishing a link between a cause and an effect.
- Trustworthiness: Ensuring that the observed relationship is real and not due to extraneous factors.
- Controlling Variables: The need to account for or minimize the influence of confounding variables that could offer alternative explanations for the results.
The reference also contrasts this with external validity: "External validity refers to the extent to which results from a study can be applied (generalized) to other situations, groups, or events."
Internal Validity in Qualitative Research: A Different Perspective
While the provided definition specifically mentions "causal relationship," qualitative research typically does not aim to establish cause-and-effect in the same way quantitative experiments do. Instead, qualitative research seeks to understand experiences, explore perspectives, describe phenomena, or build theory within specific contexts.
Therefore, applying the exact quantitative definition of internal validity directly can be misleading. In qualitative research, the concept most closely aligned with internal validity is often referred to as trustworthiness or credibility.
Credibility in qualitative research means ensuring that the findings are believable and accurate from the perspective of the participants and that they faithfully represent the data collected. It is about the confidence in the truth of the findings, mirroring the spirit of the quantitative definition's "degree of confidence that the relationship... is trustworthy," even though the "relationship" studied isn't necessarily causal.
Think of it this way:
| Aspect | Quantitative (Internal Validity) | Qualitative (Credibility/Trustworthiness) |
|---|---|---|
| Primary Goal | Establish causal relationships; test hypotheses | Explore experiences, understand meaning, describe phenomena |
| Focus | Confidence in cause-effect link | Confidence in the truth and accuracy of the description/interpretation |
| Main Concern | Ruling out alternative causal explanations | Ensuring findings accurately reflect the data and participant reality |
| Key Question | Is the effect truly due to the cause? | Do the findings ring true for the participants and context? |
Ensuring Trustworthiness (Qualitative Equivalent)
Qualitative researchers employ various strategies to enhance the trustworthiness and credibility of their findings, which serves a similar purpose to ensuring internal validity in quantitative studies. These include:
- Prolonged Engagement: Spending sufficient time in the field with participants to build trust and understand the culture or context deeply.
- Persistent Observation: Focusing on relevant characteristics of the situation being observed to identify patterns and gain in-depth understanding.
- Triangulation: Using multiple sources of data (e.g., interviews, observations, documents), methods (e.g., different interview approaches), researchers, or theories to corroborate findings.
- Member Checking: Taking findings back to participants to confirm that they resonate with their experiences and perspectives.
- Peer Debriefing: Discussing the research process and findings with impartial colleagues to challenge assumptions and explore potential biases.
- Detailed Methodological Description: Providing a thick description of the research process, context, and participants, allowing others to evaluate the rigor of the study.
These techniques help qualitative researchers ensure that their interpretations are grounded in the data and reflect the reality of the phenomenon under study, providing confidence in the accuracy and truthfulness of their conclusions, much like internal validity provides confidence in quantitative findings.
In essence, while the term "internal validity" isn't always used directly in qualitative research and the definition from the reference applies primarily to causal studies, the underlying principle of ensuring the findings are accurate, trustworthy, and well-supported by the data remains critically important. Qualitative researchers achieve this through demonstrating the credibility and trustworthiness of their work.
