Abstract:
The purpose of this research was to investigate the internal consistency reliability, test-retest reliability and the differences of reliability coefficients of the Likert Attitude Scale, which contained three, four, five, six and seven categories of response; groups were tested and retested under one, two, three and four week intervals. The Likert Scale used for data collection included an Attitude Scale towards Teaching Professional. The sample employed in this research consisted of 620 students at the first year level of The Higher Certificate in Education from Bansomdej Choapraya Teachers College, Thonburi Theachers College, Suan-Sunanta Teachers College and Chandrakasem Teachers College. The data were analyzed by computing the reliability coefficient, using Cronbachs Alpha Coefficient for the internal consistency reliability and The Pearson Product Moment Correlation for the test-retest reliability. The fishers Z Transformation was employed in comparing the reliability of attitude scale. The research results were: 1. In the first test, the internal consistency reliabilities of The Likert Attitude Scale, containing responses from three to seven categories, showed no significant differences at 0.5 level. The reliability coefficients of the scale which contained responses five, and seven categories were higher than those of three and four categories. 2. In the retest, the internal consistency reliabilities of the Likert Attitude Scale containing responses from three to seven categories showed no significant differences at 0.5 level, and the reliability coefficients of the scale were found to be independent of the number of scale points. 3. The test-retest reliability coefficients of the Likert Scale containing responses from three to seven categories showed no significant differences at 0.5 level. The test-retest reliability coefficients of the scale which contained responses from three to seven categories were independent of the number of scale steps employed. The test-retest reliability coefficient of the scale tested at intervals of two and three weeks were higher than one and four weeks.