* Reliability and validity of the test - these are the characteristics of the research compliance with formal criteria that determine the quality and suitability for use in practice.
What is reliability?
In the course of checking the reliability of the test, an assessment of the constancy of the results obtained during repeated testing is carried out. Data discrepancies should be absent or minor. Otherwise, it is impossible to relate to the test results with confidence.
Reliability of the test is a criterion that testifies to the accuracy of measurements. The following test properties are considered significant:
- reproducibility of the results obtained from the study;
- the degree of accuracy of the measurement procedure or related instruments;
- sustainability of results over a period of time.
In the interpretation of reliability, the following main components can be distinguished:
- the reliability of the measuring tool (namely, the literacy and objectivity of the test task), which can be estimated by calculating the corresponding coefficient;
- the stability of the studied trait over a long period of time, as well as the predictability and smoothness of its fluctuations;
- objectivity of the result (i.e., its independence from the personal preferences of the researcher).
Reliability factors
A number of negative factors can affect the degree of reliability, the most significant of which are the following:
- imperfection of the methodology (incorrect or inaccurate instructions, fuzzy wording of tasks);
- temporary instability or constant fluctuations in the value of the indicator that is being studied;
- inconsistency in the environment in which the initial and repeated studies are carried out;
- the changing behavior of the researcher, as well as the instability of the state of the subject;
- subjective approach in evaluating test results.
Methods for assessing the reliability of the test
In determining the reliability of the test, the following methods can be used.
The retest method is one of the most common. It allows you to establish the degree of correlation between the research results, as well as the time in which they were carried out. This technique is simple and effective. Nevertheless, in subjects, as a rule, repeated studies cause irritation and negative reactions.
The method of checking internal consistency does not take into account the constancy of the results obtained by repeated research. He establishes the relationship of the answers that were given in the framework of one experiment. Test questions are divided into two lists (according to a specific principle), after which the correlation coefficient between the results is calculated.
The method of equivalent forms consists in using two or more tests with different formulations of tasks, but with the same essence, form and degree of difficulty of execution. The reliability of the test is evidenced by the same or approximate results that were obtained using the same measuring device or computational formula. If the results strongly diverge, then most likely they were deliberately distorted or the subject did not take a very responsible approach to the survey process.
What is validity?
Test validity is a criterion that determines the validity of a measurement. We can say that this is the suitability of one or another tool for evaluating a certain psychological characteristic. It is worth noting that the validity and reliability of the test are complementary criteria; individually, they are insignificant.
Validity can be considered from the point of view of theoretical and pragmatic aspects. In the first case, we are talking about an assessment method or a measuring tool. As for the second understanding of validity, it relates to the purpose of conducting research activities. It is worth noting that this criterion may differ significantly for the same test, depending on the circle of subjects. The highest score can fluctuate around 80%.
The validity of a psychological test can be evaluated in accordance with quantitative or qualitative indicators. In the first case, we are talking about mathematical calculations. A qualitative assessment is made descriptively, based on logical conclusions.
Types of test validity
The following main types of test validity are distinguished:
- constructive validity of the test is a criterion used in evaluating a test with a hierarchical structure (used in the process of studying complex psychological phenomena);
- criterion validity implies comparing test results with a subject’s level of development of a particular psychological characteristic;
- content validity determines the relevance of the methodology to the phenomenon being studied, as well as the range of parameters that it covers;
- prognostic validity is a qualitative indicator that allows one to evaluate the prospective development of a parameter.
Types of Validity Criteria
The validity of the test is one of the indicators that allows you to evaluate the adequacy and suitability of the methodology for studying a particular phenomenon. There are four main criteria that can affect it:
- criterion of the performer (we are talking about the qualifications and experience of the researcher);
- subjective criteria (the subject's attitude to a particular phenomenon, which affects the final result of the test);
- physiological criteria (health status, fatigue and other characteristics that can have a significant impact on the final test result);
- randomness criterion (takes place in determining the probability of the occurrence of an event).
The validity criterion is an independent source of data on a particular phenomenon (psychological property), the study of which is carried out through testing. Until the results obtained are checked for compliance with the criterion, validity cannot be judged.
Key criteria requirements
External criteria that affect the indicator of the validity of the test must meet the following basic requirements:
- correspondence to exactly the sphere in which the study is conducted, relevance, as well as semantic connection with the diagnostic model;
- the absence of any interference or sharp gaps in the sample (the point is that all participants in the experiment must comply with predetermined parameters and be in similar conditions);
- the studied parameter should be reliable, constant and not subject to sharp changes.
Validation Methods
Validation of tests can be done in several ways.
Evaluation of obvious validity involves checking the conformity of the test to its intended use.
An assessment of substantive validity is a check of a methodology for the presence in it of all the components necessary for a comprehensive study of a particular phenomenon or factor.
Assessment of constructive validity is carried out in the case when a series of experiments are conducted to study a certain complex indicator. It includes:
- convergent validation - verification of the relationship of estimates obtained using various integrated techniques;
- divergent validation, which consists in the fact that the methodology does not imply the evaluation of extraneous indicators that are not related to the main study.
Evaluation of prognostic validity implies the establishment of the possibility of predicting the prospective fluctuation of the studied indicator.
conclusions
The validity and reliability of tests are complementary indicators that provide the most complete assessment of the fairness and significance of research results. Often they are determined simultaneously.
Reliability shows how much you can trust the test results. This refers to their constancy at each repeated test with the same participants. A low degree of reliability may indicate intentional misrepresentation or an irresponsible approach.
The concept of test validity is associated with the qualitative side of the experiment. It is a question of whether the selected tool corresponds to an assessment of a psychological phenomenon. Here, both qualitative indicators (theoretical assessment) and quantitative (calculation of the corresponding coefficients) can be applied.