2.3. Randomization
To ensure an equal balance of intervention and control groups in each county, stratified randomization via county was practiced. All schools were given a random number ranging from 0 to 1 using a randomization command in Stata 14 statistical software. Stata generated a random number based on a chosen key. Next, the schools were sorted according to the magnitude of the random number in each stratum. The school with the highest number was allocated to intervention group 1, I1 (DSP only), the one with the second highest number to intervention group 2, I2 (DSP and MHST), and the third highest to the control group, C. This procedure was repeated until all schools in each stratum were appointed to a group.