The process of choosing an instrument to conduct an investigation may be based on two principal indicators, that is to say on validity and reliability. The two notions are applied to the evaluation of scientific research, as they show the quality of information extracted from a specific finding. The issue of trustworthiness that can be attributed to particular empirical data and results is poignant in any research field. Validity and reliability may serve as a basis for building a scientific study and distinguishing a reputable hypothesis from those that are not supported factually.
Figure 9.2 shows three potential combinations that validity and reliability form jointly – their ratio may be used in this way to indicate the value of a measurement instrument. The target, in this case, is a metaphorical representation of the correlation between the notions in question, its center is the concept that a researcher aims to measure, and the shots are the quality with which the goal is reached. Figure 9.2a shows an instrument that is neither valid nor reliable – the quality of measurement in this scenario is the lowest. The second figure demonstrates sufficient reliability; still, validity is not attained. It could imply that incorrect values for a large number of interviewees, for instance, are being evaluated. Figure 9.2c shows an image, where the heart of a target is hit, demonstrating the highest validity and reliability. Therefore, the figure constitutes one of the ways to see the relationships between validity and reliability.
To consider the research conducted in the domain of social work objective, it needs to be based on proper methodology. For instance, if a researcher wants to establish whether assembly-line workers at a factory are content with their labor conditions, the notion of satisfaction would be the center of the metaphorical target. When the right values are evaluated for all the respondents, and the consistent group estimate is reached, the research corresponds to figure 9.2c and may be declared valid and reliable.
The term validity is used to indicate the degree to which measurements correspond to the concepts that these measurements should reflect. Face validity answers the question to what degree an instrument, such as a test or an assessment, reaches its specified goal. Construct subtype of validity appears to determine the degree of interpretation adequacy that was constructed with a method applied to empirical data of theory. Content validity shows whether an instrument is appropriate to evaluate the principal aspects of a concept. Additionally, it is usually used to measure attributes of the present. Criterion validity may be viewed as an evaluation of the level to which a measurement corresponds to an outer standard about the notion under consideration. An example of this criterion implementation is a language test that is supposed to determine the level of learners’ knowledge and divide them into corresponding groups. If the test predicts the learners’ language competence adequately, then it passed the criteria.
The concepts used in social work theories, such as democracy, public, and representation, are not as easy to quantify. Hence, indicators that only indirectly correspond to the concepts that they represent are used. And in this case, there is a danger that the selected indicators will inadequately reflect the concepts that are measured. To be valid, researches should be comprehensive and complete. Nonetheless, ensuring validity is often considered a significant issue related to measurement in social sciences.