What are the different threats to internal validity in experimental research?

There are several different threats to internal validity in experimental research. These include:

1. History: This refers to any external events or factors that occur during the course of the experiment and could potentially influence the results.

2. Maturation: This refers to the natural changes that occur in participants over time, which could affect their responses or behavior during the experiment.

3. Testing: This refers to the potential for participants to become more familiar with the experiment or measurement procedures over time, leading to changes in their responses.

4. Instrumentation: This refers to any changes in the measurement tools or procedures used during the experiment, which could affect the consistency or accuracy of the data collected.

5. Selection bias: This occurs when the process of assigning participants to different groups or conditions in the experiment is not random, leading to differences between groups that could influence the results.

6. Experimental mortality: This refers to the loss of participants during the course of the experiment, which could introduce bias if the reasons for dropout are related to the variables being studied.

7. Regression to the mean: This refers to the tendency for extreme scores or measurements to move closer to the average over time, which could affect the results if participants are selected based on extreme scores.

8. Diffusion of treatment: This occurs when participants in different groups or conditions communicate with each other and share information about the experiment, potentially influencing their responses or behavior.

9. Compensatory equalization: This refers to participants in different groups or conditions receiving additional resources or attention to compensate for perceived inequalities, which could affect the results.

10. Compensatory rivalry: This occurs when participants in different groups or conditions compete with each other and try to outperform each other, potentially influencing their responses or behavior.

It is important for researchers to be aware of these threats and take steps to minimize their impact in order to ensure the internal validity of their experimental research.