Ch_01_Wooldridge_5e_PPT

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!ooldridge" #ntroductory $cono%etrics"A Modern Approach, &e

Chapter 1

'he (ature o)$cono%etrics and$cono%ic *ata




'he (ature o)$cono%etricsand $cono%ic *ata

What is econometrics?

$cono%etrics + penggunaan aedah statisti untu

%enganalisis data eono%i

Typical goals of econometric analysis

Menganggaran hubungan antara pe%boleh ubah eono%i

Mengu-i teoriteori eono%i dan hipotesis

Ra%alan pe%bolehubah eono%i

Menilai dan %elasanaan era-aan dan dasar perniagaan




Steps in econometric analysis

1/ $cono%ic %odel this step is o)ten sipped/

2/ $cono%etric %odel

Economic models

Mungin %iro atau %acro%odels

ering %enggunaan %engopti%u%an tingah lau , %odel

esei%bangan , ...

Meu-udan hubungan antara pe%boleh ubah eono%i

Contoh " persa%aan per%intaan , persa%aan harga, ...

'he (ature o) $cono%etricsand $cono%ic *ata




Economic model of crime (Becker (1968

*erives euation )or cri%inal activity based on utility %ai%i4ation

5entu )ungsi hubungan yang tida dinyataan

6ersa%aan boleh telah %endalilan tanpa %odel eono%i

7ours spent incri%inal activities

8!age9 o) cri%inal activities

!age )or legal

e%ploy%ent :therinco%e 6robability o) getting caught

6robability o)

conviction i) caught

$pectedsentence

Age





Model latihan er-a dan produtiviti peer-a

Apaah esan daripada latihan ta%bahan %engenai

produtiviti peer-a ;

'eori eono%i ras%i tida benarbenar diperluan untuterbitan persa%aan "

:ther )actors %ay be relevant, but these are the %ost

i%portant ;/

7ourly age

<ears o) )or%aleducation <ears o) or

)orce eperience

!ees spentin -ob training





Econometric model of criminal acti!ity

'he )unctional )or% has to be speci=ed

>ariables %ay have to be approi%ated by other uantities

Measure o) cri%inal activity

!age )or legale%ploy%ent

:therinco%e

?reuency o)prior arrests

?reuency o)conviction

Average sentencelength a)ter conviction

Age

@nobserved deter%inants o) cri%inalactivity

e.g. %oral character,age in cri%inal activity,)a%ily bacground



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Econometric model of "o# training and $orker prod%cti!ity

&ost of econometrics deals $ith the speci'cation of the error

Econometric models may #e %sed for hypothesis testing

?or ea%ple, the para%eter represents eBect o) training on age

7o large is this eBect; #s it diBerent )ro% 4ero;

7ourly age <ears o) )or%aleducation

<ears o) or)orce eperience

!ees spentin -ob training

@nobserved deter%inants o) the age

e.g. innate ability,uality o) education,)a%ily bacground




Econometric analysis re%ires data

)i*erent kinds of economic data sets

Crosssectional data

'i%e series data

6ooled cross sections

6anelLongitudinal data

Econometric methods depend on the nat%re of the data %sed

@se o) inappropriate %ethods %ay lead to %isleading results




Deratan rentas set data

Contoh individu, isi ru%ah , =r%a , bandar , negeri, negara , atau

unit lain yang %enari pada titi %asa tertentu dala% te%poh

tertentu

6e%erhatian eratan rentas adalah lebih atau urang bebas

ebagai contoh , persa%pelan raa tulen daripada pendudu

Dadangadang persa%pelan raa tulen dilanggar , %is unit

enggan bertinda balas dala% a-i selidi, atau -ia persa%pelan

dicirian oleh elo%po

*ata eratan rentas biasanya dihadapi dala% %iroeono%i

gunaan




:bservation

nu%ber

7ourly age

#ndicator variables1+yes, 0+no/


Cross+sectional data set on $ages and other

characteristics



Cross+sectional data on gro$th rates and co%ntry

characteristics

Adult secondaryeducation rates

Eovern%ent consu%tionas percentage o) E*6

Eroth rate o) realper capita E*6




dataMasa siri

6e%erhatian pe%bolehubah atau beberapa pe%bolehubah dari

%asa e %asa

ebagai contoh , harga saha%, bealan ang , indes harga

pengguna , eluaran dala% negara asar , adar pe%bunuhan

tahunan , -ualan ereta , ...

Masa pe%erhatian siri biasanya diaitan bersiri

usunan pe%erhatian %enya%paian %alu%at penting

Deerapan *ata " harian , %ingguan , bulanan , suu tahun, setiap

tahun , ...

Ciri has dari siri %asa " trend dan ber%usi% Apliasi tipial "

%aroeono%i digunaan dan eangan




Time series data on minim%m $ages and related

!aria#les

@ne%ploy%entrate

Averagecoverage rate

Average %ini%u%age )or given year

Eross nationalproduct




Deratan rentas

diu%pulan *ua atau lebih eratan rentas digabungan dala%

satu set data Deratan rentas telah disediaan secara bebas

daripada satu sa%a lain

Deratan rentas diu%pulan sering digunaan untu %enilai

perubahan dasar

contoh "

Menilai esan perubahan dala% cuai harta pada harga ru%ah

a%pel raa harga ru%ah bagi tahun 1FF3

atu sa%pel raa baru harga ru%ah untu tahun 1FF&

5andingan sebelu% selepas 1FF3 " sebelu% re)or%asi , 1FF&"

selepas pe%baharuan /




,ooled cross sections on ho%sing prices

(u%ber o) bathroo%s

i4e o) housein suare )eet

6roperty ta

5e)ore re)or%

A)ter re)or%




6anel atau data %e%bu-ur

5egitu unit eratan rentas diiuti dari %asa e %asa

*ata 6anel %e%punyai eratan rentas dan di%ensi siri %asa

*ata 6anel boleh digunaan untu %enga%bil ira unobservables

%asa ta berubah

*ata 6anel boleh digunaan untu %e%odelan -aapan tertinggal

contoh "

tatisti -enayah City G setiap bandar diperhatian dala% dua tahun

Ciriciri bandar tida diperhatian %asa ta berubah bolehdi%odelan

Desan polis e atas adar -enayah %ungin %enun-uan %asa lag




T$o+year panel data on city crime statistics

$ach city has to ti%e

series observations

(u%ber o)police in 1FHI

(u%ber o) police in 1FF0





Ca%sality and the notion of ceteris pari#%s

&ost economic %estions are ceteris pari#%s %estions

-t is important to de'ne $hich ca%sal e*ect one is interested

in

-t is %sef%l to descri#e ho$ an e.periment $o%ld ha!e to #e

designed to infer the ca%sal e*ect in %estion

*e=nition o) causal eBect o) on "

J7o does variable change i) variable is changed

but all other relevant )actors are held constant9





Ca%sal e*ect of fertili/er on crop yield

J5y ho %uch ill the production o) soybeans increase i) one

increases the a%ount o) )ertili4er applied to the groundJ

#%plicit assu%ption" all other )actors that inKuence crop yield such

as uality o) land, rain)all, presence o) parasites etc. are held =ed

E.periment0

Choose several oneacre plots o) landG rando%ly assign diBerent

a%ounts o) )ertili4er to the diBerent plotsG co%pare yields

$peri%ent ors because a%ount o) )ertili4er applied is unrelated

to other )actors inKuencing crop yields





&eas%ring the ret%rn to ed%cation

J#) a person is chosen )ro% the population and given another

year o) education, by ho %uch ill his or her age increase; J

#%plicit assu%ption" all other )actors that inKuence ages such

as eperience, )a%ily bacground, intelligence etc. are held =ed

E.periment0

Choose a group o) peopleG rando%ly assign diBerent a%ounts o)

eduction to the% in)easable/G co%pare age outco%es

6roble% ithout rando% assign%ent" a%ount o) education is

related to other )actors that inKuence ages e.g. intelligence/





E*ect of la$ enforcement on city crime le!el

J#) a city is rando%ly chosen and given ten additional police

ocers, by ho %uch ould its cri%e rate )all; J

Alternatively" J#) to cities are the sa%e in all respects, ecept that

city A has ten %ore police ocers, by ho %uch ould the to

cities cri%e rates diBer; J

E.periment0

Rando%ly assign nu%ber o) police ocers to a large nu%ber o)

cities

#n reality, nu%ber o) police ocers ill be deter%ined by cri%e rate

si%ultaneous deter%ination o) cri%e and nu%ber o) police/





E*ect of the minim%m $age on %nemployment

J5y ho %uch i) at all/ ill une%ploy%ent increase i) the %ini%u%

age is increased by a certain a%ount holding other things =ed/;

J

E.periment0

Eovern%ent rando%ly chooses %ini%u% age each year and

observes une%ploy%ent outco%es

$peri%ent ill or because level o) %ini%u% age is unrelated

to other )actors deter%ining une%ploy%ent

#n reality, the level o) the %ini%u% age ill depend on political

and econo%ic )actors that also inKuence une%ploy%ent




© 2013 C L i All Ri ht R d M t b d i d d li t d t d t bli l ibl b it i

Testing predictions of economic theories

$cono%ic theories are not alays stated in ter%s o) causal eBects

?or ea%ple, the e.pectations hypothesis states that long ter%

interest rates eual co%pounded epected short ter% interest rates

An i%plicaton is that the interest rate o) a three%onths 'bill should

be eual to the epected interest rate )or the =rst three %onths o) a

si%onths 'billG this can be tested using econo%etric %ethods


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