The participants were 604 teachers of schools under the Office of the Basic Education Commission of Thailand.
The size of the experimental group was determined according to the criterion of Hair et al., (2010). Multi-stage
random sampling was used to select the sample from Northern, Central, Southern, and North eastern regions. The
theoretical framework was reviewed to build the measurement model for development of the OCB scale; these were
obtained from the idea by Organ et al. (2006) and Gokturk (2011).Then, the teachers’ OCB instrument was designed
and inspected by the specialists before pre-testing for quality inspection was conducted.