Summary Essay Example | Topics and Well Written Essays - 250 words - 64

Summary - Essay Example The impact of the violation of the local independence assumption on both reliability and information function was also evident where the study results showed that if the items were treated as a locally independent (which is in fact in violation of the items local independence), the reliability coefficient would then be biased to the top as well as the information for the test function. According to (Chen & Wang, 2007) they used index Q3 in the study to detect the items which including violation of local independence assumption. Then through simulation data according to the three parameter model , the results indicate that if it appeared that a violation of the local independence assumption between the items were corrected, then they were locally independent. This affects the estimated parameter discrimination where if the violation is positive, then to answer the first item correct increases the probability of the correct answer on the other item. The discrimination parameter estimate will then be biased upwards while at the same time, if the violation of local independence between items will be negative, then the discrimination parameter estimate will be biased to the downwards. Chen and Thissen (Chen & Thissen, 1997) used Q3,, to examine the local independence of items and a test was generated. As the results indicate, there are two types of local dependence between the items. First one is known as (ULD) Underlying Local Dependence and this type of local dependence is shown by the items there. There are some separate traits for items groups showing local dependence, but not for all the test items. This means that there is another traits which is not the general trait measured by the test. The second type of local dependence is known as (SLD) Surface Local Dependence, and this type of local dependence of items is shown in the