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KINH T HC QUN L (Managerial Economics)

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Chng 2 Ch

c lng v d on cu

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Ni dung chng 3Phn tch co dn ca cu c lng cu g D on cu

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co dn ca cu theo gi g co d ca cu theo gi (E) dn h i ( )Phn nh phn trm thay i trong lng cu ca mt mt hng khi gi ca mt hng thay i 1% Cng thc tnh: %QE= %P

Do lut cu nn E lun l mt s m Gi tr tuyt i ca E cng ln th ngi mua cng phn ng nhiu trc s thay i ca gi c

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co dn ca cu theo giCc gi tr co dn: E > 1 E < 1 E = 1 %Q> %P: cu co dn Q %Q< %P: cu km co dn %Q= %P: cu co dn n v %Q

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co dn v tng doanh thu gKhi cu co dn, vic tng gi s lm gim doanh thu v gim gi s lm tng doanh thu g g g Khi cu km co dn, vic tng gi s lm tng doanh thu v gim gi s lm gim doanh thu Khi cu co dn n v, tng doanh thu t gi tr ln ht l nht

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Cc yu t tc ng n E y gS sn c ca hng ha thay thCc hng ha thay th i vi mt hng ha hoc dch v cng tt v cng nhiu th cu i vi hng ha hay dch v cng co dn

Phn trm ngn sch ngi tiu dng chi tiu cho hng ha Phn Ph trm trong ngn sch tiu dng cng ln cu cng h i d l co dn

Giai on iu chnh Thi gian iu chnh cng di th cu cng co dn7

Tnh co dn ca cu theo gi g co dn khongQ PTB E= P QTB

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Tnh co dn ca cu theo gi g co dn im khi ng cu tuyn tnh Xt hm cu tuyn tnh y Q = a + bP + cM + dPR

Q = a'+ bPTrong b = Q/P

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Tnh co dn ca cu theo gi g co dn im khi ng cu tuyn tnh S dng mt trong hai cng thc g g g

P E =b QTrong :

hoc

P E= PA

- P v Q l gi tr ca gi v lng ti im tnh co dn - A (= a/b) l h s ct ng cu (im giao gia trc gi (=-a /b) v ng cu10

Tnh co dn ca cu theo gi g co dn im khi ng cu phi tuyn S dng mt trong hai cng thc sau g g gE= Q P P = P Q P A

Trong : Q/P l dc ca ng cu ti im tnh co dn P v Q l gi tr ca gi v lng ti im tnh co dn A l im giao gia trc gi v ng thng tip xc vi ng cu ti im tnh co dn

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co dn thay i dc theo ng cui vi ng cu tuyn tnh, P v |E| thay i tnh cng chiu dc theo ng cu tuyn tnhGi tng, cu cng co dn tng Gi gim, cu cng km co dn

i vi ng cu phi tuyn, khng c quy lut chung v mi quan h gia gi v co dnDo c dc v t l P/Q u thay i dc theo ng cu Mt trng hp c bit Q = aPb, co dn ca cu theo gi lun khng i (=b) vi mi mc gi12

Doanh thu cn binDoanh thu cn bin (MR) l s thay i trong tng doanh thu khi sn lng bn ra thay i mt n v Cng thc tnh:TR MR = Q

MR chnh l dc ca ng tng doanh thu TR

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Cu v doanh thu cn bin Xt hm cu tuyn tnh P = A + BQ ( > 0, B < 0) Q (A , )Hm doanh thu cn bin cng tuyn tnh, ct trc gi ti cng mt im vi ng cu v c dc gp i so vi dc ng cu MR = A + 2BQ

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ng cu tuyn tnh, MR v E g y

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MR, TR v EDthu co dn ca Tng d T doanh thu h th cn bin cu theo gi TR tng Elastic d MR > 0 Co dn khi Q tng (E> 1) 1) (E>(P gim)

MR = 0 MR < 0

TR max TR gim khi Q tng (P gim)

Co elastic Unit dn n v (E= (E= 1) 1) Inelastic dn Km co (E< 1) 1) (E 0 i vi hng ha thng thng EM < 0 i vi hng ha th cp

EM

%Qd Qd M = = %M M Qd

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Co dn ca cu theo gi cho gCo dn ca cu theo gi cho (EXY) o lng phn ng trong lng cu hng ha X khi gi ca hng ha c lin quan Y thay i (tt c cc yu t khc c nh) )EXY > 0 nu hai hng ha thay th EXY < 0 nu hai hng ha b sung

E XY

%Q X Q X PY = = %PY PY Q X19

c lng cuXc nh hm cu thc nghim c lng cu ca ngnh cho hng chp nhn gi g g g p g c lng cu cho hng nh gi

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Xc nh hm cu thc nghimHm cu tng qut Q = f (P, M, PR, T, Pe, N) ( , , ) B qua bin T v Pe do kh khn trong vic nh lng th hiu v vic xc nh k vng v gi c Nh vy hm cu c dng: Q = f(P, M, PR, N) Ch v vic thu thp s liu c lng cu

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Xc nh hm cu thc nghim gXc nh hm cu thc nghim tuyn tnhHm d H cu c dng Q = a + bP + cM + dPR + eN Ta c b = Q/P c = Q/M d = Q/PR Du d tnh ca cc h s

e = Q/N

b mang du m c mang du dng i vi hng ha thng thng v mang du m i vi hng ha th cp d mang du dng nu l hng ha thay th v mang du m nu l hng ha b sung e mang du dng22

Xc nh hm cu thc nghim gXc nh hm cu thc nghim tuyn tnh g yQ = a + bP + cM + dPR + eN

Cc gi tr co dn ca cu c c lng l

=bP E Q =cM EM Q = d PR E XR Q23

Xc nh hm cu thc nghim gXc nh hm cu thc nghim phi tuyn Dng thng dng nht l dng loga tuyn tnh g g g g g y

Q = aP b M c PRd N e c long hm cu dng ny phi chuyn v loga t nhin lnQ = ln + b lnP + c lnM + d lnPR + e lnN lna Vi dng hm cu ny, co dn l c nh

E =b

EM = c

E XR = d24

G Gi do th trng q y nh v gi do nh g quyt g qun l quyt nhi vi hng chp nhn giGi c c xc nh bng s tng tc ng thi gia gia cung v cu Gi c l bin ni sinh ca h phng trnh cung cu bin c xc nh bi h phng trnh

i vi hng nh gi: iGi c do ngi qun l quyt nh Gi c l bin ngoi sinh

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c lng cu ca ngnh i vi hng g g g chp nhn giD liu quan st c v gi v lng c xc nh mt cch ng thi ti im m ng cung v ng cu giao nhau vn ng thiVn c lng cu ca mt ngnh pht sinh do l h h i hd s thay i trong cc gi tr quan st c ca gi v lng th trng c xc nh mt cch l h h h ng thi t s thay i trong c cu v cung.

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Vn ng thiV d v hm cung v cu ca mt loi hng ha Cu: Q = a + bP + cM + d Cung: Q = h + kP + lPI + s Do cc gi tr quan st c ca gi v lng (gi v lng cn bng) c xc nh mt cch ng thi bi cung v cu nn PE = f(M, PI, d,, s) v QE = g(M, PI, d,, s)

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Vn ng thiPE = f(M, PI, d, s) Nh vy: y v QE = g(M, PI, d, s)Mi gi tr quan st c ca P v Q c xc nh bi tt c cc bin ngoi sinh v cc sai s ngu nhin trong c phng trnh cu v phng trnh cung Cc gi tr quan st c ca gi tng quan vi cc sai s ngu nhin trong c cu v cung

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Vn ng thi

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Phng php 2SLSPhng php bnh phng nh nht hai bc Bc 1: To mt bin i din cho bin ni sinh, bin ny tng quan vi bin ni sinh nhng khng tng quan vi SSNN Bc 2: Thay th bin ni sinh bng bin i din v p dng phng php OLS c lng cc tham s ca hm hi quy

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Cc bc c lng cu ca ngnh g gBc 1: Xc nh phng trnh cung v cu ca ngnhV d c th xc nh phng trnh cung v cu nh sau: Cu: Q = a + bP + cM + dPR Cung: Q = h + kP + lPI g

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Cc bc c lng cu ca ngnh g gBc 2: Kim tra v nh dng cu ca ngnh Hm cu c nh dng khi hm cung c t nht mt g g bin ngoi sinh khng nm trong phng trnh hm cu

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Cc bc c lng cu ca ngnh g gBc 3: Thu thp d liu ca cc bin trong cung v cu Bc 4: c lng cu ca ngnh bng phng php 2SLSPhi xc nh r bin ni sinh v bin ngoi sinh

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V d minh hac lng cu th gii i vi kim loi ng Bc 1: Xc nh phng trnh cung v cu ca ngnh g Cu: Qng = a + bPng + cM + dPnhm Cung: Qng = e + fPng + gT + hX Bc 2: Kim tra v nh dng cu ca ngnh Bc 3: Thu thp d liu ca cc bin trong cung v cu Bc 4: c lng cu ca ngnh bng phng php 2SLS34

V d minh haDependent Variable: QC Method: Two-Stage Least Squares g q Date: 09/15/08 Time: 00:32 Sample (adjusted): 2 26 Included observations: 25 after adjustments Instrument list: C M PA X T Variable C PC M PA Coefficient C ff -6837.833 -66.49503 13997.74 13997 74 107.6624 Std. S Error 1264.456 31.53377 1306.344 1306 344 44.50984 t-Statistic S -5.407729 -2.108693 10.71520 10 71520 2.418845 Prob. 0.0000 0.0472 0.0000 0 0000 0.0247 5433.632 5433 632 1669.629 3870869. 1634042. 163404235

R-squared R squared 0.942143 0 942143 Adjusted R-squared 0.933878 S.E. of regression 429.3333 Durbin-Watson stat 1 465392 1.465392

Mean dependent var S.D. dependent var Sum squared resid Second-stage SSR

c lng cu i vi hng nh gi g g gi vi hng nh gi, vn ng thi khng tn ti v ng cu ca hng c th c c g g lng bng phng php OLS

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c lng cu i vi hng nh gi g g gBc 1: Xc nh hm cu ca hng nh gi Bc 2: Thu thp d liu v cc bin c trong hm cu ca hng Bc 3: c lng cu ca hng nh gi bng phng php OLS

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c lng cu cho hng Pizza g gBc 1: Xc nh hm cu ca hng Q = a + bP + cM + dPAl + ePBMac Trong :Q = d h s bn pizza ti Checkers Pizza doanh b i t i Ch k Pi P = gi mt chic bnh pizza ti Checkers Pizza M = thu nhp trung bnh trong nm ca h gia nh Westbury PAl = gi mt chic bnh pizza ti Als Pizza Oven PBMac = gi mt chic Big Mac ti McDonalds38

c lng cu cho hng Pizza g gBc 2: Thu thp d liu v cc bin c trong hm cu ca hng Bc 3: c lng cu ca hng nh gi bng phng php OLS

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c lng cu cho hng Pizza g g

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D on cuD on theo chui thi gian D on theo ma v - chu k S dng m hnh kinh t lng

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D on theo chui thi gian gMt chui thi gian n gin l mt chui cc quan st ca mt bin c sp xp theo trt t thi gian M hnh chui thi gian s dng chui thi gian trong qu kh ca bin quan trng d on cc gi tr trong tng lai

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D on theo chui thi gian gD on bng xu hng tuyn tnh: L phng php d on chui thi gian n gin nht p gp p g g Cho rng bin cn d on tng hay gim mt cch tuyn tnh theo thi gian y g

Qt = a + bt

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D on theo chui thi gian gS dng phn tch hi quy c lng cc gi tr ca a v bNu b > 0 bin cn d on tng theo thi gian Nu b < 0 bin cn d on gim theo thi gian Nu N b = 0 bin cn d on khng i theo thi gian bi d kh th i

Qt = a + bt

ngha thng k ca xu hng cng c xc nh bng cch thc hin kim nh t hoc xem xt p-value.44

D on bng xu hng tuyn tnh g g y

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V d minh haD on doanh s bn cho hng Terminator Pest ControlThe image part with relationship ID rId2 was not found in the file.

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D on theo ma v - chu k D liu theo chui thi gian c th th hin s bin ng u n c tnh ma v hoc c tnh chu k qua thi gianc lng theo xu hng tuyn tnh thng thng s dn n s sai lch trong d bo

S dng bin gi tnh n s bin ng nyKhi , ng xu hng c th b Ny ln hoc h xung ty theo s bin ng ngha thng k ca s bin ng ma v cng c xc nh bng kim nh t hoc s dng p-value cho tham s c lng i vi bin g g gi47

Bin ng doanh thu theo ma v g

2004

2005

2006

200748