( J K J T / T T (Tr.d) N (lugng m^u) So sanh giua cac td ^ l i n h Chi phi trung gian Ainh Dien tich M in h Lao dong ^ b a n g ^0.1 *0. 05 Td 1 (< 25) 4 To 2 (25 - < 30) 9 Td2/ tdi 2,29 1,52 1 , 6 8 1,36 1,79 Td 3 (30 - <35) 23 To 3/ to2 2,55 4,56 4,29 1,31 1,69 To 4 (> 3 5 ) 9 To4/ to3 2,58 4,53 1,45 1,31 1,69 £ 45
(Nguon :tinh loan tif ket qua dieu tra thtfc te nam 2004)
Bang kiem djnh tren cho thay, tlhlh > t ^ d tat ca cac tieu thu’c nguyen nhan vdi do tin cay tu 90% trd len, chung td giua cac td vSn cd su khac nhau khi suy rong mSu ra toan bd tdng thd. Vi vay ket qua phan tfch tren day cd the suy rong ra toan bo tdng the.
Qua viec phan td tren cho thay anh hudng ro cua mot sd yeu td den gia trj gia tang ciia trang trai. Cu the:
Lao dong chinh: lao dong va chat luong lao dong la nhan td quan trong trong san xuat. Sd lieu trong bang phan td tren cho thay, lao dong ty le thuan vdi gia tri gia tang cua trang trai, khi lao dong chmh binh quan la 2 , 3 3 lao dong, thi gia tri gia tang cua trang trai < 25 trieu ddng, nhung khi lao dong chmh tang len 3,89 lao dong thi gia tri gia tang dat den >35 trieu ddng.
Dien tich dat: ti le thuan vdi gia tri gia tang cua trang trai, vi la huyen mien nui, mire do ehuyen mon hoa chua cao nen khi dien tfch dat nhieu trang trai cd dieu kien san xuat do dd cho ket qua san xuat cao. Neu dien tfch binh quan dat 2,65 ha thi gia tri gia tang binh quan ciia trang trai dat < 25 trieu ddng, tuy nhien khi dien tfch tang len 8,27 ha thi gia trj gia tang cua trang trai tang len> 35 trieu ddng.
De’ thay ro mire do anh hudng cu the’ ciia tung tieu thuc nguyen nhan tdi su bien dong cua gia tri gia tang cua trang trai (tieu thuc ket qua), ta tien hanh udc luong ham san xuat Cobb-Douglas.
3.2.2. Sur dung ham san xuat Cobb-Douglas
Xay chfng ham san xuat Cobb - Douglas: Y = a(, X,al X2a2 X?3 e a4D
Logarit 2 ve difa ham san xuat ve dang tuyen tmh ta co:
L nY — I na() + a j LnX\ + ... + a j LnXj + a_f D
Trong do: Y : Gia tri gia tang cua trang trai (Tr.dong). Ky hieu la GTGT, a„: He so tu do,
a,: He so hoi quy ring voi bien thu i (i = 1,2, 3),
D = 1 Neu chu trang trai duoc hoc qua ldp tap huan ve ehuyen mon
va quan ly
D = 0 Neu chu trang trai chua duoc hoc qua ldp tap huan ve ehuyen mon va quan ly. Ky hieu la QLY,
X I : Chi phi san xuat cua trang trai (Tr.dong). Ky hieu la CPHI, X2: Sd lao dong chmh cua trang trai (LD). Ky hieu la LD,
X3: Tong dien tfch cua trang trai (Ha). Ky hieu la DTICH, Ket qua chay ham san xua't Cobb- Douglas duoc tong hop tren bang 18: