Threats to Internal Validity Explained

In Video 38 of the CHES & MCHES certification prep series, we take an in-depth look at threats to internal validity explained. This lesson falls under Area IV — Conducting Evaluation and Research, one of the core competency areas defined by the National Commission for Health Education Credentialing (NCHEC). Whether you are preparing for your initial CHES certification or advancing to the MCHES level, mastering this content is essential for exam success and professional practice.

In this video, we break down the major threats to internal validity in research and evaluation. Internal validity refers to the confidence that observed effects are actually caused by the intervention.

Area IV focuses on Conducting Evaluation and Research Related to Health Education. This area tests your knowledge of evaluation design, data analysis, and evidence-based decision making. Understanding both formative and summative evaluation is essential for demonstrating program effectiveness.

Understanding what internal validity means and why it matters is a key component of this competency area. The NCHEC expects certified health education specialists to demonstrate not only theoretical knowledge of this concept but also the ability to apply it in real-world public health scenarios. Understanding major threats: history, maturation, testing, instrumentation, regression to the mean is a key component of this competency area. The NCHEC expects certified health education specialists to demonstrate not only theoretical knowledge of this concept but also the ability to apply it in real-world public health scenarios. Understanding selection bias, attrition, and diffusion of treatment is a key component of this competency area. The NCHEC expects certified health education specialists to demonstrate not only theoretical knowledge of this concept but also the ability to apply it in real-world public health scenarios. Understanding how to minimize threats to internal validity is a key component of this competency area. The NCHEC expects certified health education specialists to demonstrate not only theoretical knowledge of this concept but also the ability to apply it in real-world public health scenarios. Understanding key exam scenarios involving internal validity threats is a key component of this competency area. The NCHEC expects certified health education specialists to demonstrate not only theoretical knowledge of this concept but also the ability to apply it in real-world public health scenarios.

This topic appears frequently on the CHES and MCHES certification exams. Scenario-based questions in this area often require you to identify the most appropriate course of action given a specific public health context. Pay close attention to the distinctions between similar concepts, as NCHEC exam writers frequently use closely related answer choices as distractors. Reviewing this material alongside practice questions will help reinforce your understanding and improve your test-taking confidence.

As you work through this content, consider how each concept connects to the broader health education process. The NCHEC exam blueprint emphasizes the integration of knowledge across all Areas of Responsibility. A strong candidate understands not only the individual competencies but also how assessment, planning, implementation, evaluation, advocacy, communication, leadership, and ethics work together in professional practice. Use this video lesson as a starting point, then deepen your understanding through additional study resources available at subthesis.com.