Q td —g db (6.21)
6.3.2.Thai 4n digu chinh gia Ca Va san liking
Chong ta se tiep tuc phan tich ye Ong thai cUa gia ca va san luong bang viec (lira ra d6ng thi cac tiled han dieu chinh cau va gia cung ctia cac nha san xuat. Hinh 6.6 xay dung (trong c16 thi voi hai truc P va Q) cluOng cung cUa cac nha san xuat va duerng cau tieu &mg. Giao diem E xac Binh gia ca va san luong can bang (mO hinh tuong Ong duoc mO to o phan tren). Gia thiet rang, d6i lap voi mO hinh tru6c day, cac nha san xuat an Binh gia ca va va san lacing tieu thu.
Tai diem tren duOng cung P*(Q), vi du tai diem A tren hinh 6.6a, san luong duoc yeu cau bOi nhEing ngued tieu thy se cao hon voi san luong t6i tru cUa cac nha san xuat theo mac gia nay (diem S' tren dtrOng cung) va gia se thap hon gia t6i tru cita cac nha san xuat theo mac san xuat nay (diem S" tren clueing cung). Do vay cac nha san xuat se nang gia len (m[ii ten haat-1g len tren diem A) bOi vi dieu do cho phep lam thoa man va lap day luong cau du thira (S'A). Bay giO ta hay khao sat d6 thi voi vi tri la nguei tieu thu. Tai pi-11a cluOi duOng cau OP), vi du tai diem A tren hinh 6.6a, gia cao hon so voi gia ma ngtrOi fiat dung san sang tra de mua voi san Wong Q (gia nay tiring ang voi diem D' tren dung cau); milt cau cUa ngued tieu thy se thgp hon so voi mac gia hien nay Witt t6i uu wing Ong voi diem D" tren duOng cau). Do vay cau c6 xu huong giam (milli ten hiking phia trai diem A).
Tuong to nha vay, ta tiep toe khao sat ba mien tiep theo. Dua tren ket qua khdo sat, ta co the: mO to tien trinh cUa gia ca va san luong. Tien trinh nay se dua lai mot chu trinh hei to ve diem can bang E. Viec hOi to film to la rat don dieu neu tiled han dieu chinh gia ca va san luong khac nhau Ion; nguoc lai viec hOi to se phirc tap theo long xDay Iron O-c neu cac tiled han nay tiep can gan nhau. Nhu vay su khac nhau ma mO hinh Cobweb dua ra la o cho gia ca va san luong tien tridn theo huOng cl6i lap nhau, con tien tridn cua chu trinh thi mang tinh lien tyc hon. Tai diem A, cau du thira (hinh 6.6b), gia ca tang va san xuat giam nham khdc phgc
(lam mat di) su du thira nay; viec giam cau dan den viec giam gia (diem B) va sir sut giam ye gia se keo theo dung cau quay ngugc lai (diem C); nhu vay hic nay gia lai tang len (didrn D),...
\fed tam . nhin vi mo, clueing cung duoc thiet lap nen tir the dgng mang tinh chu Ic57 cUa hai nhan to gia ca - tin luong, va dgrig thai cUa gia ca phu thugc chit yeu vao su dieu chinh mac luong thuc Ce. Ngoai ra, clOng thai cita cau se nhanh hon nhieu lan so \Jai Ong thai cua gia ca va tien luong (se duoc trinh bay 6 phan 6.4 sau day).
b) ► Q s', P(Q) P • OP) F s A Zt: N D
Hinh 6.6. Chu trinh gia ca - san hwng Tac ding cila thin han diet' chinh cUa cung va cau a) Gia dtroc dieu chinh cham; b) Gia dugc diet' chinh nhanh. a)