Internal Validity vs. External Validity

Summary

The script differentiates between internal and external validity in research. Internal validity assesses the accuracy of study results, such as whether smoking causes periodontal disease. It's enhanced by eliminating extraneous variables, having a large sample size, and using proper data analysis. External validity, conversely, measures the ability to generalize findings to the broader population. Ensuring a representative sample size and unbiased sampling techniques are crucial for good external validity. The script emphasizes the importance of both types of validity for credible research.

Takeaways

• 🔍 Internal validity refers to the accuracy of the results within a study.
• 🌟 Ensuring a good and strong study design enhances internal validity.
• 🧐 Eliminating extraneous variables and creating a comfortable environment for participants strengthens internal validity.
• 📈 A large sample size and proper data analysis contribute to a study's internal validity.
• 📚 Longitudinal studies, which are conducted over a long period, improve internal validity more than cross-sectional studies.
• 🌐 External validity is about the ability to generalize study findings to real-life situations.
• 👥 A diverse and representative sample size is crucial for good external validity.
• 🔎 Checking for biases in the sample helps to ensure external validity.
• 🔄 The more people included in a study, the better its external validity.
• 🌟 Both internal and external validity are essential for a study's credibility and applicability.

Q & A

What is internal validity?

Internal validity refers to the accuracy of the results in a study, determining whether the conclusions drawn from the study are true and can be trusted.

How is internal validity ensured in a study?

Internal validity is ensured by conducting a strong study that controls for extraneous variables, has a large sample size, collects good data, and uses appropriate data analysis methods.

What role does the sample size play in determining internal validity?

A larger sample size generally contributes to better internal validity because it can provide more reliable and generalizable results.

How does a longitudinal study contribute to internal validity?

A longitudinal study, which is conducted over a long period, can improve internal validity by allowing researchers to observe the effects of a variable over time, thus strengthening the accuracy of the study's results.

What is external validity?

External validity is the ability to generalize the findings of a study to a larger population or real-life situations outside the specific conditions of the study.

How can a researcher check for external validity?

A researcher can check for external validity by ensuring that the study's sample is representative of the larger population and that sampling techniques are unbiased.

Why is it important to have a comfortable environment for participants in a study?

A comfortable environment for participants helps to control for extraneous variables that could affect the study's results, thus contributing to better internal validity.

What is the difference between a cross-sectional and a longitudinal study in terms of validity?

A cross-sectional study provides a snapshot at one point in time, while a longitudinal study observes changes over a longer period. Longitudinal studies typically offer better internal validity due to their extended observation period.

Can you provide an example of how a study might lose internal validity?

A study might lose internal validity if it fails to control for confounding variables, has a small sample size, or if data collection and analysis methods are flawed.

How does the presence of bias in a study affect its external validity?

Bias in a study, such as selection bias or measurement bias, can skew the results, making them less representative of the larger population and thus reducing the study's external validity.

What is the relationship between internal and external validity?

Internal validity is a prerequisite for external validity. A study must first have accurate results (internal validity) before its findings can be generalized to other populations or situations (external validity).