The method of parallel or alternative forms consists in creating two equivalent tests to measure the degree of correlation between the items. The most commonly used procedure is the two-half procedure, in which the items are divided into two groups after the test is answered then the correlation between the two halves is analyzed. In order to measure reliability, three procedures are used basically: the method of two halves, that of parallel shapes and the test-retest.
/internal-and-external-validity-4584479_final-a1cf2c26ce464856bb86fe5ceb99b17b.png "psychology validity and reliability")
The information they provideĪlthough this is a somewhat simplistic way of approaching it, it is generally claimed that validity indicates that a psychometric tool actually measures the construct it seeks to measure, while reliability refers to know if it is measured correctly, without errors. On the other hand, the validity does not refer exactly to the instrument but to generalizations made from the results obtained through this. Reliability is a characteristic of the instrument, in that it measures the properties of the elements that compose it. Differences between reliability and validityĪlthough these two psychometric properties are closely related, the truth is that they refer to clearly differentiated aspects. Finally, concept validity is intended determine if the test measures what it intends to measure, For example of convergence with scores obtained in similar tests. The instrument must include all the fundamental aspects of construction for example, if we are to do an appropriate test to measure depression, we will necessarily have to include items that assess mood and decrease in pleasure.Ĭriterion validity measures the ability of the instrument to predict aspects related to the plan or area of interest. We can basically distinguish between content validity, criteria (or empirical) validity and concept validity.Ĭontent validity defines the extent to which the items in a psychometric test are a representative sample of the items that make up the concept to be assessed. There are different types of validity, which depend on how it is calculated this makes it a term with very different meanings. Likewise, in scientific research, a high validity indicates the extent to which the results obtained with a given instrument or in a study can be generalized. This concept is defined as the relationship between the score obtained on a test and another related measure the degree of linear correlation between the two elements determines the coefficient of validity. When we talk about validity, we are referring to whether the test correctly measures the construct it intends to measure.
Psychology validity and reliability free#
Therefore, a high reliability coefficient indicates that scores on a test fluctuate little internally and over time and, in short, that the instrument is free from measurement errors. The first concept indicates that scores change little when measured on different occasions, while internal consistency refers to the extent to which the items that make up the test measure the same psychological construct. The two main components of reliability these are temporal stability and internal consistency. Thus, the direct score of a test would consist of the sum of the random error and the actual score. Reliability excludes predictable errors, that is, those which are subject to experimental control.Īccording to classical testing theory, reliability is the proportion of variance explained by true scores. The higher the reliability of an instrument, the lower the number of random and unpredictable errors that will appear when using it to measure certain attributes. In psychometry, the concept of “reliability” refers to the precision of an instrument more precisely, the reliability coefficients inform us of the consistency and stability of the measurements taken with this tool. The relationship between the two concepts
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