However, a more general evaluation

However, a more general evaluation is also require: Is the experiment valid? Have we made valid measurement of the effects of the independent variable? (Box 6-2 presents an important measurements validity issue to consider) We can talk about two kind of validity when we look at the experiment as a whole. The first is internal validity – the degree to which a researcher is able to state a causal relationship between antecedent conditions and the subsequent observed behavior. Later in the book we will discuss external validity, how well the finding of the experiment generalize or apply to situations that were not tested directly (for example, real life). But before we can think about the external validity of an experiment, we must first evaluate its internal validity