Validity is essentially a complex characteristic, including, on the one hand, information about the suitability of the method for measuring the purpose for which it was created, and on the other hand, what are its effectiveness, efficiency, and practical utility.
Internal validity is a component of the validity of knowledge, action, and results of these actions in scientific studies. Relative adjective “internal” is the ratio of one attribute of an object of research to other attributes within the same object without generalization to other objects, another place, another time of studying, and other conditions of the study. Internal validity is a property that characterizes the veracious conclusion about the causal relationship between two or more variables within this study (no generalization to other objects, other times, a place of research, and other conditions of the study).
An example could be the fact that in assessing the relationship between the construct of “reason” and construct “effect” exist dependence. Internal validity of this conclusion characterizes it corresponds to the real relations (in the scope of this research is to study the object for a given time and place of study). Internal validity does not characterize the operation of the construct that is not to say, how well the researcher operation construct a theoretical model. Internal validity of conclusions of the study in the absence of construct validity is possible.
External validity means the possibility of generalization of conclusions based on the availability and dissemination to other facilities, the time periods outside studied in experimental situations. Suppose somebody want to understand the extent to which the sale of the products will change if one changes the price. To do this, put the following experiment: offer options to participants catalogs with different prices, they buy products from these directories. Then analyze these choices are analyzed. Such experiments are actually carried out and the results give the illusion of much higher than it really is the sensitivity of consumers to the price factor. There is fact that the attention of the participants in this experiment artificially concentrates on the other parameters.