Chu de 2 Stata_VHLSS

Khoa Kinh t pht trin D n Trng H Kinh t TPHCM Nghin cu nh lng vi VHLSS

Ch 2. STATA & VHLSS

1. Gii thiu Stata Vi Stata:

1. Thao tc (nhanh chng) bng cu lnh;

2. Lu tr kt qu:

Chn ni lu tr kt qu (th mc lm vic): File > Change working directory . cd "C:\...\Desktop\OutputStata11"

Dng lnh : log using file_output, text lu kt qu. . log using 7Aug2010, text

Trong , file_output l tn file kt qu (7Aug2010); text file_output c nh dng text. Trong qu trnh lm vic, dng lnh log off tm thi dng hnh ng lu tr;

lnh log on m li chc nng lu tr; log close thot ra file lu tr.

3. To mi v thc thi dofile: dng lnh doedit to mt dofile, sau t tn cho

dofile (v d : vhlss2008.do) v lu vo th mc lm vic. thc thi dofile, dng

lnh do dofile_name (v d: do vhlss2008).

2. Cc cng c c bn trong Stata

---------------------------------------------------------------------------------------------------------------------------------------------- Thanh V, Email: [email protected] Ghi ch bi ging 1


2.1 Thng k m t

Cu lnh Din gii

describe M t d liu (Describe a dataset)

summarize Thng k m t (Descriptive statistics)

tabulate To bng tn s mt hoc hai chiu (One- and two-way frequency tables)

table To bng (thng k m t)

tabstat To bng thng k m t (Table of descriptive statistics)

histogram Biu tn s

graph V th

2.2 Qun l d liu

Cu lnh Din gii

describe M t d liu

save; edit Lu tr, chnh sa d liu

Generate/egen; replace; recode To bin mi; thay th gi tr ca bin; m ha li

keep; drop Gi li hay xa bin/quan st

label; format To nhn cho bin; nh dng hnh thc

append; merge Ghp ni quan st, cc file

rename i tn bin

sort; gsort; order Sp sp th t quan st theo gi tr; th t cc bin

2.3 Phn tch phng sai

Cu lnh Din gii

ttest t-test

oneway; anova ANOVA

correlate; pwcorr Tng quan

2.4 Phn tch hi quy

Cu lnh Din gii

regress Hi quy tuyn tnh

logistic; logit; probit Hi quy logistic; logit; probit

3. Thc hnh Stata



S dng file hhexpe08.dta

3.1 Lnh use ti d liu

. use "D:\VHLSS\VHLSS08\Data\Hhold\hhexpe08.dta", clear

. use http://fmwww.bc.edu/ec-p/data/wooldridge/CEOSAL1

(Introductory Econometrics: A Modern Approach by Jeffrey M. Wooldridge (1st &

2d eds.) , Chapter 2 - The Simple Regression Model; Example 2.3: CEO Salary and

Return on Equity)

. use http://fmwww.bc.edu/ec-p/data/wooldridge/WAGE1

3.2 Lnh describe (c th vit tt : d) m t tp d liu (s quan st, s bin, tn bin trong tp d liu).

. d

. d hh*

Lnh tabmiss xem c gi tr missing. . tabmiss

. tabmiss hh*

3.3 if v in

. su hhexp1rl if reg==8

. su hhexp1rl if reg>7

. sort tinh huyen xa diaban hoso

. list tinh huyen xa diaban hoso riceexp in 1/10

. list tinh huyen xa diaban hoso riceexp in -10/-1

3.4 Lnh gennerate v replace

To bin mi bng lnh generate (vit tt gen)

generate newvar = exp [if exp]

exp = m t ni dung ca bin mi.

V d:

. gen weexp= waterexp+elecexp to ra bin th hin tng chi tiu v in v nc ca h gia nh (bin weexp).

. gen pcexp= hhexp1rl/ hhsize to ra bin th hin chi tiu bnh qun u ngi ca h gia nh (bin pcexp).

To bin gi trong Stata:



. gen delta1 =1 if region==2 | region==8

. replace delta1 =0 if delta1==. to ra bin th hin h gia nh sng vng ng bng/ khng phi vng ng bng.

Hoc

. gen delta2 = (region==2 | region==8)

. gen poor = 1

. replace poor = 0 if pcexp < 2930 to ra bin th hin h gia nh l h ngho (poor=1)/ khng ngho (poor=0).

To bin mi bng lnh egen: to ra cc bin mi da trn cc hm thng k. C php:

egen newvar = func_stat(varname)

Cc hm thng k thng dng func_stat():

Func_stat() Din gii

mean() Trung bnh

median() Trung v

count() m s quan st

sd() lch chun

rowmean(var1 varn) Tnh gi tr trung bnh ca n bin t var1 n varntotal() Tnh tng cng

V d:

. egen avghhexp1=mean(hhexp1rl) chi tiu trung bnh ca h.

. egen avghhexp2=mean(hhexp1rl), by(reg8) chi tiu h trung bnh theo 8 vng.

. egen totalexp1=total(hhexp1rl)

. egen totalexp2=total(hhexp1rl), by(urban08)

. egen exp123=rowmean(waterexp elecexp garbexp)

. order waterexp elecexp garbexp exp123

. display (840+3720+108)/3

3.5 Lnh sort v gsort

. sort hhexp1rl

. gsort +hhexp1rl

. format %9.0f hhexp1rl



. gsort -hhexp1rl

3.6 Lnh drop v keep

C php:

drop varlist keep varlist

Xa hoc gi li quan st. C php:

drop if exp keep if exp

3.7 Lnh summarize (vit tt: su): thc hin thng k m t c bn.

Thc hin thng k m t hoc cho tt c cc bin trong tp d liu hoc cho mt hay

mt s bin chn lc trong tp d liu. C php:

su su var1 var2 varn su, detail thc hin thng k m t chi tit, bao gm percentiles (phn v),

trung v (median), trung bnh (mean), lch chun (sd), phng sai (variance),

skewness, kurtosis.

V d:

. su hhexp1rl

. su hh*

. su waterexp if urban08==1

. su waterexp elecexp if urban08==2

Ch : if urban08 == 1 s dng 2 du =. . su hhexp1rl hhsize if reg8 == 8

. su hhexp1rl hhsize if reg8 == 8 & urban08 == 1

. su hhexp hhsize if region > 7 & urban08 == 1

3.8 To bng tn s 1 hoc 2 chiu Lnh tab to bng tn s 1 chiu/ 2 chiu. C php:

Bng 1 chiu : tab var

Bng 2 chiu : tab var1 var2. tab reg8

. tab urban08



. tab urban08 reg8

C th s dng lnh tab3way to bng tn s a chiu.

V d:

. tab3way reg8 urban08 poor

3.9 Kt hp tab v summarize Kt hp 2 lnh tab v su to ra thng k m t cho bin nh lng (cont_var1) theo

cc thuc tnh ca bin phn loi (cat_var). C php:

. tab cat_var, su(cont_var)

. tab cat_var1 cat_var2, su(cont_var)

V d:

. tab urban08, su(hhexp1rl)

. tab reg8, su(hhexp1rl)

. tab reg8 urban08, su(hhexp1rl)

th hin gi tr trung bnh ca bin nh lng theo tng thuc tnh ca 2 bin phn

loi, s dng c php: tab cat_var1 cat_var2, su(cont_var) mean

V d:

. tab reg8 urban08, su(hhexp1rl) mean

Mt s options ca lnh tab:

C php: tab var1 var2, [options]

Options Din gii

cell Tnh phn trm theo mi

row Tnh phn trm theo dng

col Tnh phn trm theo ct

chi2 Kim nh chi bnh phng (Pearson)

all a ra nhiu kim nh

V d:

. tab poor urban08

. tab poor urban08, cell

. tab poor urban08, row col

1 Bin nh tnh (bin phn loi Categorical variable).



3.10 Mt s lnh thng k m t khc

Lnh tabstat, stats() C php: tabstat var, stats(options_stats) thc hin cc thng k m t cho bin var.

Mt s thng k trong stats():

Option_stat Din gii

mean Trung bnh

median Trung v

iqr tri gia

sd lch chun

n S quan st

max Gi tr ln nht

min Gi tr nh nht

range Khong bin thin Range = Max Min

var Phng sai

cv cv=sd/mean

skewness Skewness

kurtosis Kurtosis

V d:

. tabstat hhexp1rl, stats(mean median iqr sd)

. tabstat hhexp1rl, stats(mean median iqr sd n max min range var)

. tabstat hhexp1rl, stats(mean median iqr sd n max min range var cv skewness kurtosis)

C th vit tt cu lnh v nh dng hnh thc th hin:

. tabstat hhexp1rl, s(mean median iqr sd) format(%7.2f)

Lnh tabstat vi by . tabstat hhexp1rl, stats(mean median iqr sd n max min range var) by(urban)

Lnh table, c(): to bng thng k. C php: . table cat_var, c(option_stat cont_var)

. table cat_var1 cat_var2, c(option_stat cont_var)

. table cat_var1 cat_var2, c(option_stat1 cont_var1 option_stat2 cont_var2)

V d:



. table poor, c(mean hhsize)

. table poor, c(mean hhsize sd hhsize)

. table poor, c(mean hhsize sd hhexp1rl)

. table poor urban08, c(mean hhsize)

. table poor urban08, c(mean hhsize sd hhexp1rl)

Lnh table vi by . table poor, c(mean hhsize sd foodnom) by(urban)

3.11 Biu phn phi tn s: hnh dng ca phn phi: cn i hay lch

(lch phi hay lch tri). C php:

histogram var, freq th tn s th hin s quan st tng ng. histogram var, percent th tn s th hin phn trm theo s quan st. histogram var, norm th tn s c th hin ng phn phi chun.

V d:

. histogram pcexp, freq

. histogran lnpcexp, freq norm

. histogram pcexp, percent

. histogram pcexp, norm

. histogram lnpcexp, norm

020

040

060

080

0Fr

eque

ncy

6 8 10 12lnpcexp



3.12 th hp Graph box

Cho bit thng tin v khuynh hng tp trung, phn tn, cn i v cc outlier. C php:

graph box var1 graph box varlist

V d:

. graph box edu

graph box edu workepx



iqr = Q3 Q1 Max = Q3 + 1.5*iqr

Min = Q1 1.5*iqr

3.13 Lnh merge Ghp 2 file d liu li thnh 1 file. Gi s cn ghp file1 (file master) vi file2 (file using).

- Xc nh bin (cc bin) chung ca file1 v file2;

- Sort theo bin chung (cho c 2 file);

- C php: merge [varlist] using file2



Ngun: Nicholas Minot (2002).

V d:

***** merge

*VHLSS2008

use "D:\VHLSS\VHLSS08\Data\Hhold\hhexpe08.dta", clear

gen double idhh= (10^2)*hoso+(10^4)*diaban+(10^7)*xa+(10^9)*huyen+(10^11)*tinh

format idhh %15.0f

order idhh

keep idhh hh*

foreach var of varlist hh* {

rename `var' v08`var'

}

sort idhh

save "C:\Users\TRUONGTHANHVU\Desktop\OutputStata11\hhexpe08s.dta"

*VHLSS2006

use "D:\VHLSS\VHLSS06\Data\hhold\hhexpe06.dta", clear


format idhh %15.0f

order idhh

keep idhh hh*

foreach var of varlist hh* {

rename `var' v06`var'

}

sort idhh

save "C:\Users\TRUONGTHANHVU\Desktop\OutputStata11\hhexpe06s.dta"

*MERGE

merge idhh using "C:\Users\TRUONGTHANHVU\Desktop\OutputStata11\hhexpe08s.dta"

tab _merge

_merge | Freq. Percent Cum. ------------+----------------------------------- 1 | 5,062 35.52 35.52 2 | 5,062 35.52 71.04 3 | 4,127 28.96 100.00



------------+----------------------------------- Total | 14,251 100.00

* MERGE

use "D:\VHLSS\VHLSS08\Data\Hhold\muc123a.dta", clear


format idhh %15.0f

order idhh

sort idhh

gen double idmem= matv+(10^2)*hoso+(10^4)*diaban+(10^7)*xa+(10^9)*huyen+(10^11)*tinh

format idmem %15.0f

order idmem

merge idhh using "C:\Users\TRUONGTHANHVU\Desktop\OutputStata11\hhexpe08s.dta"

tab _merge

count

count if matv==1

tab matv m1ac3

duplicates drop idhh, force

count



Ph lc

Hm ton hc (Mathematic Functions)

Cu lnh Din gii

abs(x) Gi tr tuyt i (Absolute value)

sin(x), cos(x), tan(x) Sin, cos, tang

int(x), round(x) Ly s nguyn/lm trn s

comb(n, k) Hm kt hp (Combinational function)

exp(x) Hm m Exponential function

ln(x) Logarit t nhin (Natural logarithm)

logit(x), invlogit(x) Log ca t l odd v nghch o ca n

max(x), min(x) GT ln nht v nh nht

sqrt(x) Cn bc (Square root)

sum(x) Tng cng

Hnh thc d liu (Data Types)

Dng Hnh thc Din gii

float S thc 8 ch s

double S thc 16 ch s

int S nguyn -32767 ~ 32740

long S nguyn -2,147,483,647 ~ 2,147,483,620

byte S nguyn -127 ~ 100

str# Chui (dng text) str1 n str244

Hnh thc ton t (Operators)

Dng Din gii

S hc + (cng), - (tr), * (nhn), / (chia), ^ (m)

So snh > (ln hn), >= (ln hn hoc bng), < (nh hn),


Ti liu tham kho:

1. Long, J. Scott. and Jeremy Freese. 2003. Regression Models for categorical

Outcomes Using Stata , revised edition. College Station, TX: Stata Press.

2. Nicholas Minot (2002).


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Chu de 2 Stata_VHLSS