The effects of the violation of local independence assumption on the person measures under the Rasch model
Author(s):
Abstract:
Local independence of test items is an assumption in all Item Response Theory (IRT) models. That is, the items in a test should not be related to each other. Sharing a common passage, which is prevalent in reading comprehension tests, cloze tests and C-Tests, can be a potential source of local item dependence (LID). It is argued in the literature that LID results in biased parameter estimation and affects the unidimensionality of the test. In this study the effects of the violation of the local independence assumption on the person measures in a C-Test are studied. A C-Test battery comprising four passages, each containing 25 blanks, was analysed twice. Firstly, each gap was treated as an independent item and Rasch’s (1960) dichotomous model was employed. In the second analysis, each passage was treated as a super item and Andrich’s (1978) rating scale model was used. For each person, two ability measures were estimated, one on the basis of the dichotomous analysis and one on the basis of the polytomous analysis. The differences between the two measures, after being brought onto the same scale, are compared and the implications are discussed.
Keywords:
Language:
English
Published:
Iranian Journal of Applied Linguistics, Volume:11 Issue: 1, Mar 2008
Pages:
51 to 67
magiran.com/p1081162
دانلود و مطالعه متن این مقاله با یکی از روشهای زیر امکان پذیر است:
اشتراک شخصی
با عضویت و پرداخت آنلاین حق اشتراک یکساله به مبلغ 1,390,000ريال میتوانید 70 عنوان مطلب دانلود کنید!
اشتراک سازمانی
به کتابخانه دانشگاه یا محل کار خود پیشنهاد کنید تا اشتراک سازمانی این پایگاه را برای دسترسی نامحدود همه کاربران به متن مطالب تهیه نمایند!
توجه!
- حق عضویت دریافتی صرف حمایت از نشریات عضو و نگهداری، تکمیل و توسعه مگیران میشود.
- پرداخت حق اشتراک و دانلود مقالات اجازه بازنشر آن در سایر رسانههای چاپی و دیجیتال را به کاربر نمیدهد.
In order to view content subscription is required
Personal subscription
Subscribe magiran.com for 70 € euros via PayPal and download 70 articles during a year.
Organization subscription
Please contact us to subscribe your university or library for unlimited access!