Rubber farmers' cooperatives in Thailand's special economic zones were studied to see how well they operate. The researchers used a method called two-stage data envelopment analysis to measure their efficiency. They found that cooperatives in different phases of development had efficiency levels ranging from 24% to 65%. Cooperatives in the beginning phase were less stable in their efficiency scores, while those in the developed phase were more consistent. The study showed that factors like managerial and entrepreneurial skills greatly influence the efficiency of these cooperatives. This suggests that farmers need more support to improve their business skills for long-term success.