Costs and Benefits Gained from Planting Para Rubber in the form of System of Simultaneous Equations: A Case Study of Pa Phayom District, Phatthalung Province and Thung Song District, Nakhon Si Thammarat Province

Abstract

          The objectives of this research are to investigate factors that affect the costs of planting and benefits gained from rubber selling, and then generating simultaneous equations model. Interview was used to gather information by two-stage sampling to get 391 rubber smallholder families in Pa Phayom District, Phatthalung Province and Thung Song District, Nakhon Si Thammarat Province. The results found that, the average costs and benefits gained per rai per month are 423.01 and 2,003.47 Bahts, respectively. A system of forecasting equations can be shown as follows:

Ŷ₁ = 1,294.7416 – 1,146.3597X₁₄  + 48.1285X_{16_1},

Ŷ₂ =  858.59397 – 0.81145Y₁  + 0.051X₆  + 53.98444X₁₁  – 72.38626X_{12_2}  + 385.56038X_{15_2}  + 856.106X_{16_1}  + 695.29398X_{16_2} ,

where  Y₁ and Ŷ₁ represent the cost and its forecasting value (Baths / rai / month), respectively,

       Ŷ₂   represents the forecasting value of benefit (Baths / rai / month),

       _X6   represents the number of rubber trees (trees),

       _X11   represents the number of days that can rubber tapping per month (days),

       X_{12_2}   represents the area of rubber plantation (plain area represented by 1, if not represented by 0),

       _X14   represents the method of rubber tapping (by owner represented by 1, if not represented by 0),

       X_{15_2}   represents the rubber clone (BPM24 represented by 1, if not represented by 0),

       X_{16_1}   represents the most common forms of rubber selling (rubber sheet represented by 1, if not represented by 0),

       X_{16_2}   represents the most common forms of rubber selling (fresh latex represented by 1, if not represented by 0).