Question

What is external validity? What is internal validity? Why do you need both?

Answer 1

Validity checks the authencity of the research work . It gives us the idea of any error if occurs in our work. Internal and external validity are two of the four types of validity.

Internal validity checks whether the result observed in a study is due to the effect of independent variable or it is caused due to some error or other factors. In other words it validates the relationship between the independent and dependent variable.

External validity refers to the maximum limit or the extent upto which the result of the study or experiment can be generalised or applied across the population or to the rest of the work. It is just like the assessment of sample and applying its result to the total population.

We need both of them for following reasons :

1) It checks if the conclusion of the result is correct ir not.

2). It verifies if the changes in the dependent variable is due to changes in the independent variable or due to some other reasons.

3). It checks for inaccuracy or error in the study. It also validates if the sample outcome can be applied to the population variables or not.