Describe the greatest threats to internal validity and how you would mitigate them. Also describe the greatest threats to external validity and how you would address them.

Threats to Internal Validity of Research Design

1. History:- this is the events that is observed between first and second measurements.

2. Instrumentation:- this is difference that occurs to the results due to inconsistency of the instruments

3. Maturation:- this means the longer the research, the higher the chances of sample to have outgrown or improved in their performance.

4. Testing

5. Selection Biases

6. Experimental Mortality

How to mitigate the Internal Validity threats

1. History:- Quickly identify external factors that may influence the results.

2. Instrumentation:- Ensure there is consistency on the instruments.

3. Maturation:- Reduce time if possible between pretest and post test period.

Threats to External Validity of Research Design

1. Multiple Treatment Interference:- conducting multiple treatment of the same sample are difficult to control for the effect of prior treatment.

2. Interaction Effect of Testing:- a previous test tends to influence samples' response to the variables used in experiment.

3. Interaction Effects of Selection Biases

4. Reactive Effects of Experimental Arrangements

How to mitigate the threats to External Validity of Research Design

1. Interaction effect of testing:- Avoid interaction with the sample before the test.

2. Interaction effects of selection biases:- Make use of randomization when selecting samples.

Explanation:

Internal Validity of Research Design simply means that, whether or not, the experimental conditions/treatments make difference, and whether the available evidence/results support such fact or claim being considered.

While

External Validity of research design is a means of using the outcomes /results of a particular study/research to determine cases outside that study. That is, the application of the research result to other situations or issues that need be considered.