3.9.4 Reliability
The internal reliability of 17 Likert-scaled items, which measured attitude towards helmet use, was checked by Cronbach‟s alpha reliability test. The initial alpha coefficient was 0.720, but after deleting four statements (helmet use is important for driver‟s safety, everyone should wear helmet, wearing a helmet reduces peripheral vision, and storage of helmets when the motorcycle is parked is a problem), the alpha coefficient increased up to 0.824 whereby deleting further statements had no effect in increasing the coefficient.