Abstract:
Purpose The purpose of this thesis was to construction an efficient English language proficiency test in vocabulary for Matayom Suksa three, four and five students. Procedures Initially 3 forms of an English language proficiency test was constructed. Each form had 5 parts-section I : Part A and Part B; and Section II : Part A, each with 100 items, Section II : Part B and Part C, each with 50 items. This test was pretested with two levels of students Matayom Suksa 4 and 5. Then item analyses were performed. Finally the good items were chosen from the 3 Forms, selecting only those that had suitable levels of difficulty and good discrimination power. Item were combined to make a one-Form, 100-item test. The test was administered the second time with Matayom Suksa 3, 4 and 5 students in 6 schools. The number of students amounted to 678. Then scores were re-analysed and other item statistics were gained. Results From the item analysis results, the Matayom Suksa 3 level had 72 good items, Matayom Suksa 4 had 88 good items, and Matayom Suksa 5 had 89 good items. There were 63 items that were good in all three classes, 35 items which were good in some classes and 2 items that were not good in any of the classes. The reliability of the test for Matayom Suksa 3, 4 and 5 was .89, .93 and .93, respectively. The Means of the test for Matayom Suksa 3, 4 and 5 were 32, 45, 40.68 and 49.75, respectively. Comparison of the difference between the Means of Matayom Suksa 3, 4 and 5 showed that the Means of Matayom Suksa 5 and 4 were higher than the Mean of Matayom Suksa 3 at the significant level of .01 and the Mean of Matayom Suksa 5 was higher than that of Matayom Suksa 4 at the significant level of .01.