chufin h6a
Danh myc bao hi~m * Muãc dQ hai long Crosstabulation
Muc d◊ hai long Total Khonghai Trung Hai
long l~p long
Count 40 16 12 68
Bao hi~m ti~n Expected
32.6 24.5 10.9 68.0
gui Count
Adjusted
Residual 2.2 -2.6 .5
Count 32 24 16 72
Danh mvc bao Expected
34.6 25.9 11.5 72.0
hiem Bao hi~m y t€ Count Adjusted
-.8 -.6 1.8
Residual
Count 24 32 4 60
Bao hiem xa Expected
28.8 21.6 9.6 60.0
h(>i Count
Adjusted
-1.5 3.3 -2.4
Bang 3 .45: KSt qua tinh h~ s6 th6ng ke Chi - Square
Chi-Square Tests
Value df Asymp. Sig.
(2-sided)
Pearson Chi-Square 15.861a 4 .003
Likelihood Ratio 16.302 4 .003
Linear-by-Linear Association .429 I .512
N of Valid Cases 200
a. 0 cells (0.0%) have expected count less than 5.
The minimum expected count is 9.60.
Dàa tren kSt qua da tinh toan, ch(mg ta c6 thS thciy r~ng gia tri cua (x2) la 15. 861, Chung ta ciing c6 thS quan sat r~ng muc y nghia thc1p nhc1t dftn dSn vi~c bac bo gia thuySt Ho giua cac biSn la gia tri muc y nghia Sig.
= 0.003 < 0.05 a de) tin c~y 95%, nen gia thuySt Ho bi bac bo, dieu nay cho phep chung toi kSt lu~n r~ng c6 sà tuang quan gifra hai biSn dang nghien CUU.
Do hrirng m6i nrong quan d11a tren h~ s6 Chi - Square
Cac thu6c do m6i lien h~ chinh dàa tren th6ng ke chi binh phuang (x2) la h~ s6 Phi, h~ s6 Cramer's V va H~ s6 Contingency coefficient (C), tcit ca chung duqc ap dvng cho cac biSn djnh tinh (djnh danh). N6i chung, h~ s6 tuang quan la m<)t thu6c do thay d6i gifra 0 va 1, thS hi~n gia tri 0 khi khong c6 m6i quan h~ giua cac biSn va gia tri 1 khi ch(mg c6 m6i tuang quan hoan hao. Chung ta se xem tirng cai m<)t cua cac h~ s6 duqc nghien . cuu trong phfrn nay hot;1t d<)ng lien quan dSn cac d~c diSm nay.
❖ H~ s6 Phi
Do luong m6i quan h~ gifra cac biSn djnh danh, h~ s6 Phi biSn thien tu -1 dSn + 1. Do d6, h~ s6 nay ngoai kha nang chi ra m6i quan h~ va cuong de) cua m6i quan h~ n6 con chi ra hu6ng cua m6i quan h~ d6.
H~ s6 Phi chi dung cho dt;1ng bang 2x2 (2 dong, 2 c<)t) Cong thuc:
Phi=~
Vi dv:
D~ cung dp dich V\l . ch~t lm;mg cao va dap ung mong dgi cua khach hang, m()t cong ty trong nganh thai trang nam, dang dAu tu vao cac chiSn luge d~ phan khuc thi truang. Hi~n t~i, cong ty c6 bf>n cua hang 6 Thanh phf> H6 Chi Minh, nAm 6 phia B~c, Trung tam, phia Nam va phia Dong cua thanh phf>, va ban bf>n lo~i quAn ao: ca-v~t, ao so mi, ao Polo va quAn dai. Bang du li~u cho th~y mua hang cua 20 khach hang, lo~i quAn ao va dia di~m cua cua hang. Ki~m tra xem c6 mf>i quan h~ nao gifra hai biSn bAng h~ s6 Phi khong.
Bang 3.46: Dfr li~u mua hang cua 20 khach hang
Khach hang Quin ao Khu VlfC
1 Ca-v~t Phia Nam
2 Ao polo Phia Bile
3 Ao sa mi Phia Nam
4 Quful Phia Bile
5 Ca-v~t Phia Nam
6 Ao polo Trung tam
7 Ao polo Phia Dong
8 Ca-v~t Phia Nam
9 Ao sa mi Phia Nam
10 Ca-v~t Trung tam
11 Quful Phia Bile
12 Quful Trung tam
13 Ca-v~t Trung tam
14 Ao polo Phia Dong
15 Quful Trung tam
16 Ca-v~t Trung tam
17 Quful Phia Nam
18 Quful Phia Bile
19 Ao polo Phia Dong
20 Ao sa mi Trung tam
Gia tri cua thf>ng ke chi binh phuang la x2 = 18.214. Do d6:
Phi= l8ã214 = 0.954
Vi ca hai biSn c6 bf>n 10<;1.i, trong truang hqp nay, diSu ki~n -1 ~Phi
~ I khong hqp 1~, gay kh6 khan cho vi~c di Sn giai mire d9 tuang quan cua hai biSn.
❖ H~ sf> Contingency coefficient (C)
H~ sf> Contingency coefficient ( C) la m9t thu6c do mf>i tuang quan khac cho cac biSn dinh danh d\Ia tren thf>ng ke x2.
Cong thuc:
c--
Trong d6 n la kich thu6c mftu
H~ sf> Contingency coefficient (C) dugc su d\lng cho bang ma sf>
c9t va hang la bftt ky, c6 gia tri thftp nhftt la 0, chi ra rAng khong c6 mf>i tuang quan gifra cac biSn. Tuy nhien, gi6i h<;1.n cao nhftt cua C thay d6i my thu9c vao sf> lugng danh ID\lC, vi v~y:
Trong d6:
q = min(l,J)
Trong d6: I la sf> hang va J la' sf> c9t trong bang.
c- {q=-T '
Khi ~q c6 m9t S\J kSt hgp hoan.hao gifra cac biSn; Tuy nhien, gi6i h<;1.n nay khong bao gia gia dinh gia tri 1. Do d6, hai M sf> Contingency coefficient (C) Ghi c6 th~ dugc so sanh nSu ca hai dSu dugc xac dinh tu cac bang c6 cung sf> hang va CQt.
Vi d\l:
Tinh h~ sf> Contingency coefficient (C) cho du li~u tren.
Ta tinh C nhu sau:
_18_.2_14_ = 0.690
20 + 18.214
Vi bang c6 4 dong 4 c9t (q = min(4,4) = 4). Vi th6, cac gia tri C n~m trong khoang:
0 s Cs {I ➔ 0 s Cs 0.866
~4 .
Chung ta co th€ kSt lu~n r~ng c6 m6i tuong quan gifra cac bi6n khu
V\JC ma qu&n ao mua sim cua khach hang.
❖ H~ s6 V cua Cramer
M9t thu6c do m6i quan h~ khac cho cac biSn dinh danh dàa tren th6ng ke la M sf> V cua Cramer, dugc tinh b~ng:
Trong d6:
q = min(l,J)
06i voi bang cheo cua hai bi6n c6 2x2 (2 dong, 2 c9t), biSu thuc tinh V se la:
Tuong ung v6i h~ s6 Phi. H~ s6 V cua Cramer la m9t thay thS cho h~ s6 Phi va h~ s6 Contingency coefficient (C). Gia trj cua n6 luon bi gi6i h~n trong khoang [O, 1], bfrt k€ sf> lugng danh mvc trong bang cheo c6 nhiSu hang va c9t khac nhau:
Gia tri O chi ra r~ng cac biSn khong c6 bfrt ky m6i quan h~ nao va
Vi d\l:
Tinh tinh h~ s6 V cua Cramer tiSp theo cho du li~u trong vi d\l tren.
18.214 = 0.551 20 *3
KSt qua cho thfty, 0 ~ V ~ 1 nen kSt lu~n c6 m6i quan M giua hai
bi~n. Tuy nhien, n6 chua duqc coi la nit m~nh.
Tinh toan cac h~ s6 Phi, Contingency va Cramer's V cua b~ng each su dl;lng SPSS.
Ma file du li~u SPSS ten c3dl9 _quanao.sav.
Yao Menu Analyze-+-Descriptive Statistics-+-Crosstabs ....
Ch9n biSn c~n hiSn thi dua qua dong va c{>t, Nhftn vao Statistics ... , ch9n cac my ch9n Contingency coefficient and Phi and Cramer's V. Hinh minh h9a nhu sau:
ti Crosstabs: Statistics
le.I C!}i-square
Nominal---.
~ C.Qntingency coefficient
~ !Phi and Cramer's V !
ã•- ,,O>h<hooo<a,, •• ,F ... OHằ<••" ããã•ããã• ... ,.;
lr] Lambda
t] ~ncertainty coefficient
X
!Cl Correlations Ordina1---.
IE] Qamma IE] §omers' d IL] Kendalrs tau-b ltj Kendall's tau-s;
[
Nominal. by. lnterva.1 7 IC) J:Sappa
lo Eta !El Risk
lt:i .McNemar ID Cochr~n•s and Mantel-Haenszel statistics
Iest common Odds ratio equals:
Hinh 3.29: Tuy ch9n Contingency coefficient and Phi and Cramer's V K~t qua hi~n ra, chuong trinh SPSS tinh duqc cac gia tri cua h~ s6 Phi, Contingency va Cramer's V