The instrument that one selects should have validity. The instrument should give results that reveal what they primarily aimed to measure or evaluate. An investigation can be ruled on altogether in terms of interior validity after its deductions are precise for the studied sample, and exterior validity, once its results are indiscriminate to the additional perspectives and populace domains. The capacity to extrapolate or generalize the outcomes to other zones in the country should be revealed in the exterior validity of the study (Bastos et al., 2014).
It is important for the researcher to be careful when selecting instruments to be used in scientific research so as to have a concrete hypothetical foundation and not to be seen as a mere whim. Eventually, the erroneous select of a tool can jeopardize the interior rationality of the research, generating deceptive results that are consequently incapable of answering the study question initially framed.