Bai giang SPSS 6

8/3/2019 Bai giang SPSS 6

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Chng 6KIEM NH

Chung ta lap cac bang phan tch tm bang chng e chng

minh cac gia thuyet nhng phan tren eu da tren mau (

cac phieu ieu tra ) ch khong phai tren tong the.

e xem ket qua cua mau co ung vi tong the hay khongchung ta phai thc hien cac phep kiem nh.

Kiem nh la bc th hai sau thong ke mo ta va cung la

bc quyet nh y ngha va gia tr cua cong trnh nghien

cu. Trong chng nay, xin gii thieu mot so phep kiem nhn gian :


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I-Kiem nh moi quan he gia hai bien nh

tnh

1- Kiem nh Chi-Square: c s dung pho bien khi kiemnh moi lien he 2 bien nh tnh khong th bac, hoac 1th bac vi 1 bien khong th bac:

Cach thc hien nh mo ta bang cheo tren, tai hopCrosstabs ta chon Chi-square.

c s dung e kiem nh xem co ton tai moi quan hegia 2 yeu to ang nghien cu trong tong the.

Muon thc hien kiem nh ta thc phai phat bieu gia

thuyet: H0 la khong ton tai moi quan he gia hai bien.


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Cach thc hien kiem nh Chi - Square tren SPSS

Chon Analyze -> Descriptive Statistics -> Crosstabs


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Bien phu thuoc

Bien oc lap

1

2

3

4


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Chon muc Chi - -square:

a bien gii tnh vao cot, va bien mc song vao dong ta

co 3 bang ket qua, 2 bang tren nh cua Bassi Table, bang

th 3 nh sau:

Chi-Square Tests

1.497a 3 .683

1.500 3 .682

.112 1 .738

288

Pearson Chi-Square

Continuity Correction

Likelihood Ratio

Linear-by -Linear Association

N of Valid Cases

Value df

Asymp. Sig.

(2-sided)

2 cells (25.0%) hav e expected count less than 5. The

minimum expected count is 1.96.

a.


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Tai cot Asymb Sig (2- sided ), dong au tien Pearson Chi

Square neu:

Du Sig < 0.1 th gia thuyet H0 b bac bo vi o tin cay tren90%.

Du Sig < 0.05 th gia thuyet H0 b bac bo vi o tin cay tren95%. Khi o ket luan la co ton tai moi quan he gia gii

tnh cua chu ho va mc song gia nh.

Trong v du nay Sig = 0.683 co ngha la gia thuyet H0 c chap

nhan, v nu ta bcbgithuyt th sphm sai lmrtln.

Khi kiem nh Chi Square chu y neu co qua 20% so o co

tan suat ky vong di 5 th kim nh Chi Square khong contin cay. Trong v du nay co ti 25% so o co tan suat ky

vong nho hn 5.


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Chu y: thong ke Chi-squarekhong phai la so o

mc o chat che cua moi quan he. V du khong

the ket luan rang moi quan he gia gii tnhva

mc song la quan trong, v no ch co y ngha

thong ke (tc la cac thong ke nay khong thehien mc o chat che cua moi quan he). Khi thao

luan cac ket qua can xem xet mc o quan he

trong mau cung nh y ngha cua no (va phan tram

theo dongva cot).


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Mot so ai lng khac ve moi lien he 2 bien

nh danh

Do kiem nh Chi-square khong cho biet mc o chat che gia2 bien, ta co the s dung Tables e mo ta moi lien he ohoac s dung cac ai lng thong ke do Pearson e xuat nh:

* Cramer V: Ky hieu V co gia tr 0


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2- Kim nh mi quan h 2 binnh tnh thc bc

i vi 2 bin u sp theo th bc chung ta khongdung kim nh Chi Square ma dung kiem nh tau-b,tautau-c, gamma cng trong bng Cosstabs.

Nu ct Approx Sig co kt qua


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II- Kiem nh mc o moi quan he 2 bien

nh tnh

Kiem nh Chi Square ch khang nh co moi quan he gia 2 bien

hay khong, ch khong cho biet mc o moi quan he o nh the nao.

Muon thc hien kiem nh mc o moi quan he ta dung kiem nh

Crammers V, hoax Kiem nh Lambda nam trong cung hop kiem nh Chi

Square.

Gia tr kiem nh bien thien t 0 -> 1 the hien mc o cua quan he.

h h b h


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III- Kiem nh gia thuyet ve tr trung bnh

cua 1 tong the

Phan nay se noi en viec kiem nh trung bnh cua tong

the trong trng hp mau ln va mau nho, vi ieu kien

a biet hoac cha biet phng sai tong the .

e tien hanh kiem nh thong ke cho mot gia thuyet nao

o, can thiet phai a ra nhng gia nh nao o ve d

lieu quan sat


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V d:Mt trng A, mun nh gi xem h sthng minhca hc sinh trng c hn h s

thng minh trung bnhca cc trng ton qun(105). Trng A chn ngu nhin 30 hc sinh nh gi. H s thng minh trung bnh ca hcsinh trng A c khc bit so vi ton qun ?

Gi thuyt l:

H0l hs thng minh ca hc sinh trng Akhng c s khc bit vi h s thng minh trung

bnh cc trng trong qun ( h s IQ trung bnhhc sinh ton qun = 105 ).


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Thc hien kiem nh T mot mau tren SPSS:


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Hop thoai kiem nh T mot mau:

Bien kiem nhGia tr kiem nh


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Bang ket qua kiem nh

One-Sample Statistics

30 110.73 8.05 1.47He so thong mi

N Mean Std. Dev iation Std. Error Mean

One-Sample Test

3.900 29 .001 5.73 2.73 8.74He so thong mi

t dfSig.

(2-tailed)Mean

Dif f erence Lower Upper

95% Conf idence

Interv al of the

Dif f erence

Test Value = 105


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Bang ket qua cua kiem nh trung bnh mot mau, cho ta

thay:

S khac biet trung bnh = Trung bnh mau quan sat - Trung

bnh gia thuyet.

110.73 105 = 5.73 ( bang tren )

Khoang tin cay a chon la 95% cho s khac biet gia cac

trung bnh t 2.73 -> 8.74 Gia tr kiem nh T = 3.900, vi bac t do la 29. Gia tr p =

0.001 nho hn mc y ngha (0.05 nen gia thuyet Ho heso thong minh hoc sinh trng A = 105 b bac bo. Ngha la

co s khac biet ve he so thong minh cua Trng A vicac trng trong quan.


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II -Kiem Trung bnh hai tng th

II.1 Kiem nh T vi cac mau oc lap


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Hop thoai kiem nh T hai mau oc lap :

Xac nh nhom


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III- Kim nh trung bnh 02 mu phthuc ( hay mucp )

Kim nh c dng cho 2 mu c linhvi nhau. Qu trnh kimnhbtutvic tnh ton chnh lch trn tngcpquan st theo php tnh tr.

Thng ta kim nh cho vic tin hnhcc th nghim xem s khc bit trungbnh ca l th nghim v l khng th

nghim. Gi thuyt Ho l: Khng c s khc bitgiasnphmtrc v sau th nghim.


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Thao tc trn SPSS

T Analyze -> Compare Means -> Paired Samples T Test.

Chon cap bien


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V du:

Lay mau cua 12 ngi cho mau, moi mau mau lai c chia lam

hai, mot bao quan tai ni khong co anh sangva mot e

ni co anh sang bnh thng. Bon tuan sau, tien hanh nh

lng methemoglobin va so sanh nong o MetHb hai mau

(bao quan tot: t MetHb). Ket qua nh sau:

Toi: 5.4 2.7 7.4 6.2 8.8 7.9 9.9 5.3 6.8 10.1 5.2 6.5Sang: 8.9 6.3 14.2 7.4 6.4 11.3 6.8 9.4 10.5 8.9 7.1 9.4


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Ket qua kiem nh

Paired Samples Statistics

6.850 12 2.133 .616

8.883 12 2.332 .673

Ni toi

Ni sang

Pair 1

Mean N

Std.

Dev iation

Std. Error

Mean

Paired Samples Correlations

12 .144 .656Ni toi & Ni sanPair 1N Correlation Sig.

Paired Samples Test

-2.033 2.926 .845 -3.892 -.174 -2.407 11 .035Ni toi -

Ni sang

Pair 1

Mean

Std.

Deviation

Std. Error

Mean Lower Upper

95% Conf idence

Interv al of the

Diff erence

Paired Dif f erences

t df

Sig.

(2-tailed)


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Ta co co the khang nh rang mau bao quan ni

sang kem chat lng v tang nhieu MetHb(o tin caytren 95%).

He so tng quan (Correlation) gia nong o MetHbat

trong toi va ni sang bang 0.144. He so nay co gia trdng co ngha la quan sat theo cap se lam giam s

bien thien cua cac tr trung bnh. He so tng quan

cang ln, quan sat cap cang co y ngha khi nghien

cu.


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Kiem nh trung bnh nhieu tong the (hay goi

phan tch phng sai)

- Khi kiem nh T vi 2 mau oc lap, nhng nhieu khi bienphan loai co tren 2 nhom, neu chung ta thc hien bang kiemnh Independent Sample T-Text, chung ta se phai phan thanhnhieu cap kiem nh lan lt nh vay va mat thi gian, nhngc ban la moi lan kiem nh ta chu sai so 5%, to hp cac capta chu sai lam rat ln.

- e Tranh sai lam o trong thong ke ngi ta s dung phngphap kiem nh trung bnh nhieu tong the ( phan tch phng sai) la ta kiem nh cung mot luc cac nhom va cung ch chu

sai lam 1 lan la 5%.


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Thao tac tren may


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Da bien nh lng vao

Chon phan nhom(mot bien oc lap)


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Giai thch t:

* Contrasts: Kiem nh trc

* Post Hoc : Kiem nh sau

* Descriptive: Tnh cac ai lng thong ke

* Homogeneity-of-variance: Kiem nh s bang nhau cacphng sai nhom

Chung ta thc hien kiem nh sau ngha la kiem nh

khac nhau trung bnh cac nhom sau khi thc hien phan

tch Anova, bang cach Click vao Post Hoc ta co hop

thoai:


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Y h ki h


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Y ngha cac muc kiem nh

* LSD:Chnh la kiem nh t lan lc cac cap nh kiem nh

trung bnh 2 tong the nen sai so cao. * Bonferroni: loai kiem nh nay la loai kiem nh LSDcai tien.

Dung kiem nh e thc hien tat ca cac so sanh cap gia

cac trung bnh nhom, nhng co s kiem tra tat ca cac ty le sai

so bang cach cho trc sai so ty le cho moi kiem nh( ayla kiem nh n gian thng dung).

Tukey: dung thong ke Studentized range statistice tien hanh cac

so sanh cap gia cac nhom dung e kiem nh khi co nhieu

cap trung bnh can so sanh.


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* Scheffe: thc hien so sanh cap cung mot luc cho tat ca cac ket hptheo cap co the co cua cac tr trung bnh. Kiem nh nay th kem nhaytrong viec so sanh trung bnh cua cac cap bien,nhng chnh v the ma ketqua no a ra lai than trong hn so.

* R-E-G-F: Thc hien 2 bc kiem nh, bc 1 la kiem toan bo cac trtrung bnh xem co bang nhau khong, sau o kiem nh s khac biet nhom nao.

* Dunnett: La so sanh cac tr trung cua cac nhom vi tr trung bnh cua 1nhom cu the. SPSS mac nh chon nhom cuoi e lam nhom ieu khien.

* Trong trng hp phng sai cac nhom khac nhau ta chon kiem nhTamhanes T2.

* ta chon kiem nh 2-sided (kiem nh 2 pha).

* Dau * ch s khac biet c phat hien 2 nhom tng ng dong va coto cha dau *, neu khong co dau * th kiem nh khong phat hien khac

biet cac nhom.

* Sig cho o tin cay khi bac bo gia thuyet tr trung bnh bang nhau cua cacnhom.


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V d

ANOVA

Tong dien tch chnh (m2)

147829.275 5 29565.855 29.316 .000

621257.064 616 1008.534

769086.339 621

Between Groups

Within Groups

Total

Sum ofSquares df Mean Square F Sig.


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Post Hoc Tests

Multiple Comparisons

Dependent Variable : Tong dien tch chnh (m2)

Dunnett t (2-sided)a

-60.515* 8.6747 .000 -81.106 -39.923

-54.282* 8.7900 .000 -75.147 -33.416

-40.262* 9.8006 .000 -63.526 -16.998

-1.505 10.2260 1.000 -25.779 22.769

-44.929* 10.3951 .000 -69.604 -20.253

(J) Dan toc cua gia

Khac

Khac

Khac

Khac

Khac

(I) Dan toc cua gia

Raglay

Kho

Cham

Nung

Kinh

Mean

Difference

(I-J) Std. Error Sig. Lower Bound Upper Bound

95% Conf idence Interv al

The mean diff erence is significa nt at the .05 lev el.*.

Dunnett t-tests treat one group as a control, and compare all other groups against it.a.


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c kt qu

Ti ct Mean Difference (I-J): S khc bittrung bnh tngcp nhm nu c du * l cs khc bit trung bnh ca cc cp tngng khi Sig tngngs < mc ngha

kimnh trong vd ny l 0.05.

Ktqu m ti Mean Difference (I-J): l J>I, v

d din tch Trung bnh dn tc khc > dintch trung bnh dn tc Raglay.


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Bai giang SPSS 6