1

KIM NH

GI THUYT

THNG K

Chng 8

2

Chng ny gip sinh vin:

Hiu c bn cht v cc khi nim gi

thuyt nghin cu

Bit cc bc kim nh gi thuyt

Hiu c cc loi kim nh gi thuyt

Thc hin cc kim nh thng k c bn

bng SPSS

Mc tiu chng 8

3

Ni dung chng

Cc bc kim nh gi thuyt 8.2

8.1 Khi nim v gi thuyt thng k

Kim nh v trung bnh tng th 5.4

5.5 Phn tch phng sai ANOVA

8.3 Kim nh mi lin h gia hai bin nh tnh

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8.1 Cc khi nim c bn

v gi thuyt thng k

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L mt nhn nh, gi s, nghi ng, khng nh hay

kin v mt hin tng, quan h hay tnh hung d nh

kho st

Gi thuyt l mt mnh phng on v mi quan h

gia hai hay nhiu bin s ( Kerlinger)

Gi thuyt l pht biu hin v mt vn no m

tnh xc thc ca n thng cha c bit n ( Black

& Champim)

Gi thuyt thng k l g?

6

T cc mc tiu

nghin cu, nh

NC c th thit lp

cc cu hi

nghin cu

3 dng cu hi nghin cu

1. Cu hi m t

Nhm m t hin tng

VD: KH mua hng u, ng c mua l g,

KH thch g sn phm

2. Cu hi v s khc bit

Nhm so snh s khc bit

VD: 2 nhm khch hng khc nhau c li ch tm kim

SP khc nhau khng? Cm nhn v thng hiu A

c khc thng hiu B khng? Khc im no?

3. Cu hi v s lin h

Xc nh mc lin h ca cc hin tng

VD: ng c, thu nhp c nh hng n cm nhn

v cht lng hay khng?

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Cu hi: Liu gi bn sn phm c tc ng n doanh s

bn ca doanh nghip?

- Gi thit: C mi quan h gia gi bn sn phm vi doanh s

bn ca doanh nghip, gi bn cng cao th doanh s cng

gim

Cu hi: Cc chng trnh qung co cng ty ang thc hin

c lm gia tng nhn bit ca ngi tiu dng vi sn phm

khng?

- Gi thit: Cc chng trnh qung co c tc ng n mc

nhn bit sn phm ca ngi tiu dng, qung co cng

nhiu, s c nhiu ngi bit v sn phm hn

Thit lp gi thuyt nghin cu

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Mc tiu, cu hi nghin cu v kiu thng k

Mc tiu chung Quan h gia cc bin Thun M t

Mc tiu c th So snh nhm Mc lin quan

gia cc bin Tm tt d liu

Kiu cu hi/ gi thuyt

Kiu thng k /kim nh

Khc bit S lin quan M t

Kim nh s khc bit (t-test, ANOVA)

Thng k lin quan (tng quan, hi quy)

Thng k m t

(trung bnh, mode,

bng cho)

Thng k suy din

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Gi thuyt khng: L gi thuyt m ta mun kim nh (Ho)

Gi thuyt i: Gi thuyt ngc li vi gi thuyt khng (H1)

V d:

Gi thuyt khng: Khng c s khc bit gia tui ca nam

v n, Ho: nam = n

Gi thuyt i: C s khc bit gia tui ca nam v n,

H1: nam n

Gi thuyt khng (gi thuyt thun) v gi thuyt i

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Sai lm trong kim nh gi thuyt thng k

Quyt nh v

gi thuyt khng

Ho

Bn cht ca Ho

Ho ng Ho sai

Khng bc b

(chp nhn)

Quyt nh ng

Prob = 1-

Sai lm loi II

Prob =

Bc b

Sai lm loi I

Prob =

( = mc ngha ca

kim nh)

Quyt nh ng

Prob = 1

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(V d phn ph students t)

Min chap nhan gia thuyet Ho

Min bac bo Ho

0,025

- t (/2,n-1) t/2,n-1

Gia tr t tnh c

nho hn iem ti han

Gia tr t tnh c

ln hn iem ti han

P-value

(sig.)>0,025

P-value (sig.)

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Bc 1: Thnh lp gi thuyt Ho. V d: Ho: = o

Bc 2: Thnh lp gi thuyt H1. V d: H1: o

Bc 3: Xc nh mc ngha

Bc 4: Chn cc tham s thng k thch hp cho vic kim nh,

xc nh cc min bc b; min chp nhn v gi tr gii hn

Bc 5: Tnh ton cc gi tr ca cc tham s thng k trong vic

kim nh da trn s liu ca mu ngu nhin.

Bc 6: Ra quyt nh: Nu cc gi tr tnh ton ri vo min bc

b Ho th ra quyt nh bc b Ho. Ngc li s chp nhn Ho.

8.2 Cc bc kim nh gi thuyt thng k

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Bc 1: Xc nh php kim nh cn thc hin

Bc 2: t gi thuyt

H0: khng .

H1: c

Bc 3: Thc hin kim nh bng SPSS

Bc 4: c s Sig. v so snh vi s Nu Sig. >= => chp nhn Ho

Nu Sig. < => bc b Ho

Cc bc kim nh gi thuyt bng SPSS

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8.3 Kim nh mi lin h

gia hai bin nh tnh

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Khi mun tm hiu c mi lin h no gia hai

bin nh tnh trong tng th hay khng

L kim nh ph bin trong nghin cu th trng

Kim nh c s dng l kim nh Chi-bnh

phng (Chi-Square)

p dng vi cc thang o nh danh v th bc

Kim nh mi lin h gia hai bin nh tnh

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Kim nh mi lin h gia 2 bin nh danh

- V d nh mun tm hiu mi quan h gia gii tnh v

vic chn ngnh hc

Kim nh mi lin h gia mt bin nh danh v mt bin

th t

- V d: Tm hiu mi lin h gia quan nim v cuc sng

v trnh hc vn

Kim nh mi lin h gia hai bin th t

- V d nh tui c nh hng ti mc quan tm n

ch gia nh

Cc kim nh thng gp

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gii tnh Total

Nam N

Gia nh

Quan

tam

nhat

Count 9 13 22

% within

Gia nh 40.9% 59.1% 100.0%

Quan

tam nh

Count 27 31 58

% within

Gia nh 46.6% 53.4% 100.0%

Quan

tam ba

Count 25 22 47

% within

Gia nh

53.2% 46.8% 100.0%

Total

Count 61 66 127

% within

Gia nh 48.0% 52.0% 100.0%

Quan tam ti gia nh * gii tnh Crosstabulation

Kt qu kim nh Chi bnh phng

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Chi-Square Tests

Value df

Asymp.

Sig. (2-

sided)

Pearson Chi-Square .999(a) 2 .607

Continuity Correction

Likelihood Ratio 1.002 2 .606

Linear-by-Linear

Association .989 1 .320

N of Valid Cases 127

a 0 cells (.0%) have expected count less than 5.

The minimum expected count is 10.57.

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Bng kt hp 2 bin cho ta thy dng nh c s lin

h gia gii tnh v mc quan tm ti gia nh, kt

qu cho thy n quan tm n gia nh hn nam.

Kt qu kim nh Chi bnh phng, ta c Sig. > 0.05,

nn ta khng bc b gi thuyt Ho.

Kt lun rng vi tp d liu mu, ta cha c bng

chng ni rng gii tnh c lin h vi mc

quan tm gia nh.

Kt lun

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8.4 Kim nh gi thuyt v

trung bnh tng th

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Kim nh gi thuyt

v trung bnh tng th

Kim nh

gi thuyt

s bng nhau v

tr trung bnh

ca hai tng th

Kim nh

gi thuyt

v tr trung bnh

ca mt tng th

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o Dng kim nh c hay khng s khc bit

ca gi tr trung bnh ca mt bin vi mt gi

tr c th

o p dng cho cc bin dng thang o khong

cch hay t l (bin nh lng)

Kim nh gi thuyt v tr trung bnh

ca mt tng th

Ti cho rng im trung bnh ca lp ta

l 8.5

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Tin hnh phng vn 100 khch hng v nhn hiu Tr xanh

Khng , cu hi theo thang o khong nh sau:

Q10. Anh(ch) hy cho bit mc ng ca mnh vi nhn

xt sau v Tr xanh Khng

Tr Xanh Khng l nhn hiu c nhiu ngi a thch

Hon ton

khng

ng

1 2 3 4 5

o Nh nghin cu mun kim nh xem trung bnh ca bin ny

c bng hay khc 3

V d

Hon ton

ng

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Kt qu kim nh a)Tm tt One-Sample Statistics

N Mean

Std.

Deviation

Std.

Error

Mean

Nhan hieu c

nhieu ngi a

thch

100 3.86 .792 .079

b) Kt qu kim nh One-Sample Test

Test Value = 3

t Df

Sig. (2-

tailed)

Mean

Difference

95% Confidence

Interval of the

Difference

Lower Upper

Nhan hieu c

nhieu ngi a

thch

10.86

4 99 .000 .86 .70 1.02

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Kim nh gi thuyt s bng nhau

v tr trung bnh ca hai tng th

Trng hp hai mu c lp

(gm 1 bin nh lng v

1 bin nh tnh c 2 phn loi)

Trng hp mu ph thuc hay cp mu

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Trng hp hai mu c lp

Khi mun so snh tr trung bnh v mt ch tiu nghin

cu no gia 2 nhm mu c lp

p dng cho 2 bin, bao gm:

Mt bin bin nh lng tnh trung bnh

Mt bin nh tnh dng phn loi nhm so snh

Trc khi tin kim nh trung bnh, ta cn phi thc hin

mt kim nh khc l Levene test

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Trng hp hai mu c lp(tt)

Nu gi tr Sig. trong kim nh Levene < 0.05 (SPSS

mc nh tin cy 95%) th phng sai ca hai tng

th khc nhau, ta s s dng kt qu kim nh t

phn Equal variances not assumed

Nu gi tr Sig. trong kim nh Levene > 0.05 (SPSS

mc nh tin cy 95%) th phng sai ca hai tng

th khng khc nhau, ta s s dng kt qu kim nh

t phn Equal variances assumed

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Nh nghin cu mun tm hiu c s khc nhau hay

khng gia nam v n i vi mt chng trnh

qung co ca nhn hiu X

Tin hnh phng vn 100 i tng vi 47 nam v

53 n vi cu hi dng thang o khong sau

Bn vui lng nh gi qung co ca nhn hiu X

bn va xem

V d

Rt ght Rt thch

1 2 3 4 5

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Kt qu kim nh

Group Statistics

Gii tnh N Mean

Std.

Deviatio

n

Std.

Error

Mean

Thai o

vi quang

cao

Nam 47 3.13 1.227 .179

N 53 3.60 .947 .130

Independent Samples Test

Thai o vi quang cao

Equal variances

assumed

Equal variances not

assumed

Levene's Test for Equality

of Variances

F 1.567

Sig. .214

t-test for Equality of Means T -2.185 -2.152

Df 98 86.197

Sig. (2-tailed) .031 .034

Mean Difference -.48 -.48

Std. Error Difference .218 .221

95%

Confidence

Interval of the

Difference

Lower -.909 -.916

Upper

-.044 -.036

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Trng hp mu cp

Kim nh dng cho hai bin trong cng mt mu c

lin h vi nhau

D liu thu thp t dng thang khong hoc t l

iu kin yu cu cho loi kim nh ny l kch c hai

mu so snh phi bng nhau

Cc quan st cho mi bn so snh phi c thc

hin trong cng nhng iu kin ging nhau

Ph hp vi dng nghin cu th nghim sn phm

mi hay chng trnh marketing

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Trng hp mu cp

Kim nh dng cho hai bin trong cng mt mu c

lin h vi nhau

D liu thu thp t dng thang khong hoc t l

iu kin yu cu cho loi kim nh ny l kch c hai

mu so snh phi bng nhau

Cc quan st cho mi bn so snh phi c thc

hin trong cng nhng iu kin ging nhau

Ph hp vi dng nghin cu th nghim sn phm

mi hay chng trnh marketing

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V d

Nh nghin cu mun tm hiu mc a thch vi hai sn phm

A v B. Nh nghin cu tin hnh mt cuc phng vn i tng l

100 ngi sau khi cho h dng th ln lt 2 sn phm. Cu hi

phng vn s dng thang o khong vi 5 im nh sau:

Anh(ch) vui lng cho bit mc a thch vi cc sn phm trn

1. Sn phm A

Rt khng thch Rt thch

1 2 3 4 5

2. Sn phm B

Rt khng thch Rt thch

1 2 3 4 5

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Kt qu kim nh

Paired Samples Statistics

Mean N

Std.

Deviat

ion

Std.

Error

Mean

Pair 1 San

pham

A

3.42 100 1.174 .117

San

pham

B

3.50 100 1.000 .100

Paired Samples Test

Pair 1

SP A

SP B

Paired

Differences

Mean -.08

Std. Deviation .961

Std. Error Mean .096

95%

Confidence

Interval of

the

Difference

Lower -.27

Upper .11

T -.833

Df 99

Sig. (2-tailed) .407

Bng kt qu cho thy khng c s khc bit

gia mc a thch sn phm A v B

(Sig.= 0.407 > 0.05) mc d im trung bnh ca

sn phm B cao hn sn phm B l 0.08

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8.5 Phn tch phng sai

(ANOVA)

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Phn tch phng sai

L s m rng ca kim nh trung bnh

Gip ta so snh tr trung bnh ca 3 nhm tr ln

C 2 th tc phn tch phng sai:

ANOVA 1 yu t v ANOVA nhiu yu t

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Phn tch phng sai mt yu t

c p dng trong trng hp

chng ta ch s dng 1 bin yu

t phn loi cc quan st

thnh cc nhm khc nhau

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V d

Nh nghin cu mun tm hiu c s khc nhau v tui

v mc nh gi tm quan trng ca vic c tnh yu

trong cuc sng hay khng

Bin nh lng l bin nh gi tm quan trng theo 7

mc (T 1: khng quan trng n 7: Rt quan trng).

Bin nh tnh dng phn loi l bin tui vi 4 nhm

khc nhau: (1) T 18-25, (2) t 26-35, (3) t 36 - 45 v

(4) t 46-50

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Kt qu

phn tch

a) Descriptives

Co tnh yeu

18-25 26-35 36-45 46--60 Total

N 150 140 111 99 500

Mean 5.89 5.82 5.53 5.34 5.68

Std. Deviation 1.272 1.431 1.381 1.255 1.352

Std. Error .104 .121 .131 .126 .060

95%

Confidence

Interval for

Mean

Lower Bound 5.68 5.58 5.27 5.09

5.56

Upper Bound 6.09 6.06 5.79 5.59 5.80

Minimum 1 1 1 1 1

Maximum 7 7 7 7 7

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b) Test of Homogeneity of Variances

Co tnh yeu

Levene

Statistic df1 df2 Sig.

1.607 3 496 .187

c) ANOVA

Co tnh yeu

Sum of

Square

s df

Mean

Square F Sig.

Between

Groups 22.866 3 7.622 4.250 .006

Within

Groups

889.57

2 496 1.793

Total 912.43

8 499

Bng phn tch ANOVA, vi mc ngha quan st Sig. = 0.06, gi s

chp nhn tin cy ca kim nh l 90% (mc ngha l 0.1%),

ta kt lun c s khc bit c ngha thng k gia 4 nhm tui

v s nh gi mc quan trng ca yu t c tnh yu trong cuc sng

Bng thng k m t cho ta thy mc quan trng ca yu t tnh yu

dng nh ngy cng gim khi tui cng cao.

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Cu hi n tp v tho lun

Cho bit s ging nhau v khc nhau trong 2

phng php kim nh t (cho mu cp v cho mu

c lp). Hy thit k hai nghin cu trong c s

dng hai phng php kim nh ny khi phn tch

d liu

Trong d n nghin cu m nhm anh (ch)

chn trong chng 1, hy trnh by cc phng

php kim nh m cc anh(ch) d kin s thc

hin.