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Nghien Cuu Marketing_C6 MaIT

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CHNG 6 X L D LIU Nguyn ng L X L D LIU HIU CHNH 1. Mc ch nhm m bo: ng th tc/i tng phng vn (legibility) X l cc phng vn/tr li khng hon chnh (completeness) Tnh nht qun ca cc tr li (consistency) S chnh xc ca cc tr li (accuracy) S r rng ca cc tr li (clarification) X L D LIU HIU CHNH 2. Qu trnh: Hiu chnh s b (field editing): Thc hin bi interviewer Cng sm cng tt sau khi phng vn xong Hiu chnh cui cng (office editing): Thc hin bi editor Sau khi thu thp xong data i hi ngi hiu chnh phi c nhiu kinh nghim, kin thc. X L D LIU HIU CHNH 3. X l khi pht hin li: Lin lc tr li b sung hoc lm r Hiu chnh, lm r hoc b sung theo tr nh hoc cc c liu/suy lun khc Hy b mt s cu tr li (missing value) Hy hon ton cuc phng vn/questionnaire X L D LIU M HA 1. Khi nim L qu trnh gn m s (s hoc nhn) chocc bin v cc tr li. Thang o ca bin ty thuc vo cch hi v bn cht ca bin c hi. X L D LIU M HA 2. Cc bc m ho t tn bin cho cc cu hi: Cu hi 1 chn la Cu hi nhiu chn la Chuyn tp cc chn la tr li ca mi cu hi thnh tp cc s/nhn ph hp, c ngha. Cu hi ng Cu hi m Cu hi c chn la: Khc Hai trng hp Khng bit X L D LIU M HA 3. Bn nguyn tc khi m ho: Tnh ph hp (appropriateness): Cch phn loi/nhm phi ph hp vi vn /mc tiu nghin cu.TD: Thng tin c nhn hoc doanh nghip. Tui 30 th phn phi t = phn phi z Lu : khi tra bng tc th dF = n-1 xSxt =PHN TCH N BIN KIM NGHIM GI THUYT VD: Bnh qun tui ca 100 SV trong mu l(s=5). Nh NC mun kim chng cho tng th:Null hypothesisH0:Alternative hypothesis H1:Do n=100 >30 nn dng Z test Chn mc ngha = 0.05(two tailed)Zc=1.96 TnhZ khi cha bit = (24-23) x 1001/2/5 = 2 Z = 2 > Zc = 1.96 loi H0 Khng th kt lun (vi significant 5%) l = 2324 = x23 = 23 = s n x z / ) (2 / 1 =oPHN TCH N BIN KIM NGHIM GI THUYT 2. Bin o bng thang danh xng Dng chi-square test so snh phn phi cc loi (categories) ca mu v k vng ca tng th Cc bc tin hnh:B1: Pht biu gi thuyt H0, H1 B2: Xc nh mc ngha o v bc t do df. df = k 1 (k l s loi danh nh c th chn trong bin th t) B3: Tra bng Chi-Square chun 2C_PHN TCH N BIN KIM NGHIM GI THUYT 2. Bin o bng thang danh xng (tt) B4: Tnh gi tr kim nghim theo cng thc Oi: S ln xut hin loi i trong mu Ei: Gi tr k vng ca s ln xut hinB5: Bc b/chp nhn H0 da trn tiu chun Bc b H0 nu (tnh c) > (ti hn). Ngha l c s khc bitgia phn phi ca mu v phn phi ca tng th. Kim nh Chi-Square khng c ngha khi s ln xut hin k vng cho mi la chn < 5. ==k1 ii2i i2E) E O (2_2C_PHN TCH N BIN KIM NGHIM GI THUYT VD: Kho st 100 ngi ang s dng internet HCMC. Kvngkhngcskhcnhauvnghnghipca nhng ngi s dng internet. Trong 100 ngi kho st c20nginhnvinvnphng,30ngiqunl,35 sinh vin v 15 lao ng. H0:khngcskhcnhauvnghnghipca nhng ngi s dng internet K=4 loi ngh nghip Df=k-1 = 3 = 6.25 ( vi o = 10%) V loi b H0 (Xem bng sau) 10) (122===kiii iEE O2C_ = > = 25 . 6 102 2c_ _PHN TCH N BIN KIM NGHIM GI THUYT Ngh nghipOiEiOi - Ei (Oi - Ei)2 (Oi - Ei)2/ EiLao ng1525-101004 Nhn vin VP2025-5251 Qun l30255251 Sinh vin3525101004 Total10010010 PHN TCH NH BIN KIM NGHIM GI THUYT 1. Chi Square contingency test Mc ch: Xc nh s tn ti mi quan h gia 2 bin danh nh. Yu cu: Khng c no c s ln xut hin kvng < 1 Khng qu 1/5 tng s c s ln xut hin < 5 Hn ch:Ch xc nh c quan h hay khng, khng cho bit mc quan h.PHN TCH NH BIN KIM NGHIM GI THUYT 1. Chi Square contingency test (tt) Do , thng dng h s Contingency b sung vo kim nghim Chi-Square bit mc quan h gia 2 bin. nn trong thc t hay dng h s Cramer 22nc_ +_=) 1 f ( nv2_=C = 0: khong co quan he C khong co chan tren kho dien dch V = 0: khong co quan he V = 1: co quan he hoan hao PHN TCH NH BIN KIM NGHIM GI THUYT VD:KtqukhostnhnhiuBiaathchnht phn theo mc thu nhp Thu nhpNhn hiu bia a thchTng Bia ABia BBia C Thp50 (109.38)200 (101.56)125 (164.06)375Tr.bnh200 (189.58)100 (176.04)350 (284.38)650 Cao100 (51.04)25 (47.40)50 (76.56)175 Tng350 3255251200 PHN TCH NH BIN KIM NGHIM GI THUYT Ghi ch: Con s trong ngoc ch gi tr k vng ca mi trong bng. Chng c xc nh theo t l vi tng v thu nhp v loi bia a thch. ( 1-1 c gi tr k vng = 350 x 375 / 1200 = 109.38) Tnh: ===kjijij ijliEE O1212) (2 . 2522= _Df = (k-1)(l-1) = (3-1)(3-1) = 4 Nu chn o = 1% th 3 . 132=C_PHN TCH NH BIN KIM NGHIM GI THUYT Kt lun: >2 2c_ _ Loi H0 c s khc bit ng k gia phn phi ca mu v k vng (tng th) PHN TCH NH BIN KIM NGHIM GI THUYT 2. H s tng quan Spearman v Pearson Spearman: tng quan gia 2 bin th t (ordinal). Pearson: tng quan gia cc bin khong/ t l. H s tng quan r = 0 1 (khng k du +/-) r > 0.8 rt mnh r = 0.6 0.8 mnh r = 0.4 0.6 c tng quan r = 0.2 0.4 tng quan yu r < 0.2 khng tng quan PHN TCH NH BIN KIM NGHIM GI THUYT 2. H s tng quan Spearman v Pearson (tt) Lu : Hai bin phi c phn phi chun nh bin. Phng sai ca 1 bin ti bt k gi tr no ca bin kia cng phi bng nhau. Khi r nh khng c ngha l khng tng quan, m ch khng tng quan tuyn tnh. Khi ,r, ln ch cho thy mi tng quan, nhng khng xc nh quan h nhn qu. PHN TCH NH BIN KIM NGHIM GI THUYT 3. Phn tch hi quy tuyn tnh n Phn tch 2 bin khong/t l: Hi quy tuyn tnh nY = aX + b S khc bit gia hi quy v tng quan: Hoi quy tuyen tnh Tng quan - To ra mt phng trnh ton hc lin kt cc bin li - Pht hin ra mc tng quan gia 2 bin - Tn ti gi thit nhn qu: Bin c lp Bin ph thuc- Khng c gi thit v nhn qu PHN TCH A BIN C th chia thnh hai nhm: Phn tch ph thuc: Xc nh c bin no l ph thuc, bin no l c lp.Bao gm cc pp: phn tch hi quy a bin, ANOVA, Conjoint, Discriminant, Canonical analysis... Phn tch tng tc (interdependent): Khng xc nh trc bin no l ph thuc, bin no l c lp, ch yu l tm kim cc m thc tng quan.Bao gm cc pp: Factor analaysis, Cluster, Multi-dimensional Scaling. PHN TCH PH THUC HI QUY BI Phn tch a bin gip gii quyt nhiu bi ton phc tp.Tuynhin,miphngphpphntchabin udatrnmtsgithit(ngm).Khisdng cn thn trng. Hi quy bi c dng: y = a1X1 + a2X2 + a3X3 + ... anXn + b Dng m rng ca hi quy n. Mt bin ph thuc, nhiu bin c lp Tt c c o bng thang interval (ngoi l: dummy-variable multiple regression) PHN TCH PH THUC HI QUY BI nh gi m hnh v kt qu hi quy theo 3 phn: Mc ph hp ca phng trnh hi quy: Dng h s r2 (coefficient of determination) r2 = 0 1 c trng cho % ca bin thin trong bin ph thuc c gii thch do s bin thin ca bin c lp. Kim nghim mc ngha ca r2: Dng F test(Vi t do:df = n k 1 cho mu s v df = k cho t s). Vi (n: c mu, k: s bin c lp) Kim nghim mc ngha ca cc dc ai: Dng t test vi t do df = n k 1 PHN TCH PH THUC HI QUY BI Kim nghim cc gi thuyt ca p.p. hi quy a. Linearity: C mi quan h tuyn tnh gia bin ph thuc v cc bin c lp Test: quan st scatter diagram hoc ma trn tng quanb. a cng tuyn (Multicolinearity) Gi thuyt: cc bin c lp khng c tng quan tuyn tnh vi nhau. Khi b vi phm C hin tng a cng tuyn, ngha l hin hu mi tng quan tuyn tnh gia > 2 bin c lp. PHN TCH PH THUC HI QUY BI a cng tuyn gy ra:+ Hn ch gi tr r2,+ Sai lch/i du cc h s hi quy Test a cng tuyn: h s Tolerance hoc VIF c. Phn phi chun (Normality) ca sai s v ca mi bind. Sai s hi quy c variance khng i (Constant Variance of the Error Term hay Homoscedasticity) e. Tnh c lp ca cc sai s hi quy (Independence of the Error Terms) PHN TCH PH THUC HI QUY BI Mt s lu khi s dng multiple regression: Phn tch hi quy tuyn tnh ch c ngha khi c tng quan TUYN TNH gia cc bin. r2 khng ni ln c quan h nhn qu gia cc bin C th d on sai nu nm ngoi khon tnh ton m bo tin cy phi c nhiu hn 10 im cho mi bin c lp a vo phng trnh ( yu cu c mu) PHN TCH PH THUC HI QUY BI Mt s lu khi s dng multiple regression (tt) Khong dao ng (range) cc bin c th nh hng n ngha phng trnh hi quy. Trng hp bin c lp l nominal th c th s dng dummy-variable. Khi : s bin dummy = k-1 ;vi k = s loi ca bin nominal mi bin dummy ch nhn gi tr 0 hoc 1 PHN TCH PH THUC HI QUY BI VD: Bi ton tm cc yu t quyt nh s tha mn ca nhn vin trong Cty XYZ. Bin ph thuc: s tha mn ca nhn vin Cty. Bin c lp: thu nhp, iu kin lm vic, s quan tm ca cp trn, quan h vi ng nghip, c hi thng tin, c hi hc tp, v.v. PHN TCH PH THUC ANOVA Mc ch: Kho st mi quan h gia cc bin c lp v ph thuc. c im: Tng t nh phn tch hi quy, nhng cc bin c lp l bin nonmetric (nominal/ordinal). p dng: So snh gi tr trung bnh ca mt thuc tnh (bin ph thuc/thang metric) th hin nh hng ca mt hay nhiu thuc tnh khc (bin c lp/thang nonmetric). Nu c nhiu bin c lp vi thang ch danh gi l Factorial ANOVA. Nguyn tc: Nu c s khc bit ng k gia cc nhm th between-group variance > within-group variance PHN TCH PH THUC ANOVA ** ANCOVA: c xt n cc nh hng ca mt hay nhiu bin ngoi lai (gi l control variable hoc covariates - thang o metric) v s loi ra khi tp bin ph thuc trc khi phn tch ANOVA.** MANOVA nu c nhiu bin ph thuc ** MANCOVA c nhiu bin ph thuc v bin kim sot. PHN TCH PH THUC ANOVA VD: Kho st 200 doanh nghip thuc 3 ngnh May mc, M phm v Nha gia dng v chi ph dnh cho khuyn mi hng nm. Mc ch phn tch nhm tm xem c s khc nhau ng k/ c ngha thng k gia 3 ngnh ny v chi ph khuyn mi khng? Bin c lp: ngnh (ch danh) (3 treatments) Bin ph thuc: chi ph khuyn mi (ratio) PHN TCH PH THUC ANOVA Bi ton ny c th so snh gi tr trung bnh ca chi ph khuyn mi theo tng cp ngnh (dng t test). Tuy nhin, khi s treatment ln s lng so snh s rt ln. Khi nn dng ANOVA:H0 :1 = 2 = ... = k = H1 :c t nht 1 gi tr i khc nhng gi tr kia. Vi l trung bnh ca tng thPHN TCH PH THUC DISCRIMINANT ANALYSIS DISCRIMINANT ANALYSIS (Phn Tch Phn Bit) Mc ch: Nhn ra nhng thuc tnh (cc bin c lp) phn bit cc nhm nh trc ca bin ph thuc. c im: Bin c lp c thang metric, bin ph thuc c thang nonmetric. Nguyn tc: Hm phn bit c dng: Y = v1.X1 + v2.X2 + v3.X3 + Sau khi tnh c Y, so snh vi gi tr chun Yc bit i tng thuc nhm no. PHN TCH PH THUC DISCRIMINANT ANALYSIS Cng ty my tnh mun bit xem thu nhp gia nh (X1) v s nm hc trng ca ch h (X2) c phi l hu ch trong vic phn bit h c mua my tnh PC hay khng. Kho st X1 v X2 ca 2 nhm mu ngu nhin (c v khng c PC). Bin c lp: X1 thu nhp,X2 s nm hc : metric Bin ph thuc: C PC, Khng c PC: category. Kt qu s l hm phn bit: Y= v1X1 + v2X2 v1, v2 : trng s phn bit (hng s) Y: im phn bit So snh Yi v Yc phn t i s thuc nhm no trong 2 nhm mu trn. PHN TCH PH THUC CONJOINT ANALYSIS Mc ch: Phn tch nh hng tng hp (joint effects) ca 2 hay nhiu bin c lp (thang nominal