Discuss Issues Dealings with Realibilty and Validity

Topics: Psychometrics, Reliability / Pages: 7 (1542 words) / Published: Aug 16th, 2013
ACTIVITY 4: DISCUSS ISSUES RELATED TO THE RELIABILITY OF A PSYCHOLOGICAL MEASURE
Part of long question: The activities dealing with the basic principles of psychometric theory. 6. Stage 6: Evaluating psychometric properties and establishing norms 6.1 Establishing Reliability Scheme:
1. What is meant by a person’s observed score? True score and error variance in a test score?
2. The typical sources of true variance and error variance in a test score.
3. The interpretation of a reliability coefficient and how large this value should be in order to be acceptable.
4. The interpretation of the reliability coefficient in terms of statistical significance of correlation coefficients. The difference between a high and a significant correlation.
5. Different types of reliability
a. Internal consistency- split-half reliability, Kuder Richardson 20 and Cronbach’s Alpha
b. Stability: I. Test retest stability ii. Alternate form reliability.
6. Techniques for assessing the stability of a test and advantages and limitations of each.
7. Techniques for assessing the internal consistency of a test, advantages and limitations of each.
8. The importance of the standard error of measurement.
Introduction:  Reliability is linked to how consistently an assessment measure measures what it is supposed to measure. (e.g. driving 120km, day 1, day 2 etc. Reliability: Car= 120km, not one day 100, next day 120km) ( Konsekwentheid)
 The following definition of reliability: o “The reliability of a measure refers to the consistency with which it measures whatever it measures”. o Generally, if a measure is reliable, it produces similar results when administered on repeated occasions. (Verskillende geleenthede dieselfde resultate)
 Consistency always implies a certain error in measurement due to unsystematic or chance factors present such as emotional state of mind, noise, fatigue and so forth. X (observed score) = T (true score) + E (error score) o R = the ratio of true score