Ly thuyet mau

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L THUYT MUClick to edit Master subtitle style

Tng th v mup

Tng th: k hiu X l c tnh cn nghin cu. Tp hp gm tt c nhng phn t mang c tnh X ca mt vn quan tm nghin cu gi l tng th. V d - C tri trong mt cuc bu c. - Thu nhp ca cc h gia nh Tp.HCM - im trung bnh ca sinh vin trong mt trng i hc. - Trng lng mt loi c di h.

p

Tng th v mup

S phn t ca tng th thng rt ln nn ta khng th chn ht nhng phn t thc hin th nghim v nhng l do sau:n n n

S phn t qu ln. Thi gian v kinh ph khng cho php. C th lm h hi cc phn t ca tng th.

p

V vy ngi ta s chn mt tp con ca tng th nghin cu, mt tp con nh vy gi l Mu. S phn t ca mu gi l c mu.

Tng th v mup

V d n Thm d 1000 c tri. n Kho st 100 gia nh. n Cn trng lng 50 con c. Tham s: l mt c trng c th ca mt tng th. Thng k: l mt c trng c th ca mt mu.

p

p

Tng th v muTng tha b cd o

Mub gi r y c n u

ef gh i jk l m n o p q rs t u v w x y z

Nhng gi tr c tnh ton bng s liu ca tng th gi l tham s.

Nhng gi tr c tnh ton bng s liu ca mu gi l thng k.

Chn mu ngu nhinCc phn t ca mu c chn ngu nhin t tng th. p Cc phn t ca tng th c cng kh nng c chn lm mu. p Cc phn t ca mu c chn mt cch c lp vi nhau. p Tt c nhng mu c n cng c cng kh nng c chn t tng th. Mt mu c chn tha cc iu kin trn gi l mu ngu nhin.p

Chn mu ngu nhinp

p

p

K hiu Xi l gi tr quan st X trn phn t th i ca mu. Khi ta c mt b n bin ngu nhin (X1, ..., Xn) gi l mu l thuyt ly t tng th. Tnh cht mu: n Cc Xi c cng phn phi nh X. n Cc Xi c lp vi nhau. Khi ly mu c th ta thu c b d liu (x1, .., xn) gi l mu thc nghim ly t X.

Phng php ly mu ngu nhin n ginnh s cc phn t ca tng th t 1 n N. V lp cc phiu cng nh s nh vy.Trn u cc phiu, sau chn ln lt c hon li n phiu. Cc phn t ca tng th c s th t trong phiu ly ra s c chn lm mu.

Thng k m t v Thng k suy lunp

Hai nhnh ca Thng k:n

Thng k m t: Thu thp, tng hp, v x l d liu bin i d liu thnh thng tin. Thng k suy lun: Cung cp nhng c s d on, d bo, v c lng bin i thng tin thnh kin thc.n

Thng k m tp

Thu thp d liun

Vd: Phng vn Vd: Bng v th Vd: Trung bnh mu =

p

Trnh by d liun

p

Tng hp d liun

Thng k suy lunp

p

c lng n Vd: c lng cn nng trung bnh tng th s dng cn nng trung bnh mu Kim nh gi thuyt n V d: kim nh tuyn b cn nng trung bnh bng 60 kg.Suy lun l mt qu trnh rt ra nhng kt lun hoc a ra nhng quyt nh v mt tng th da trn cc kt qu ca mu.

Qu trnh ra quyt nhQuyt nh

Kin thcKinh nghim, l thuyt, tham kho, thng k suy lun Thng tnh m my k

Thng tin B t

D liu

t, xc sut,my tnh

Cc dng d liuD liu

Phn loiV d:n

S Ri rcV d:n

n n

Tnh trng hn nhn ng k bu c? Mu mt

Lin tcV d:n n

n

S con trong 1 gia nh S ca cp cu trong 1 gi

Chiu cao in p

Cc thang o d liuVd: cn nng, chiu cao

Thang o t lD liu nh lng

Vd: mc hi lng (1 -> 5), nhit D liu phn loi c th t (xp hng, th bc, )

Thang o khong Thang o th bcD liu nh tnh

D liu phn loi (v hng hoc khng c th t)

Thang o nh danh

Trnh by d liu bng thp p

D liu dng th thng kh s dng a ra cc quyt nh. Biu din d liu di dngn n

Bng th

p

Cc dng ca th thng ph thuc vo bin c tng hp.

Trnh by d liu bng thp

Cc dng th:Bin s

Bin phn loi

Biu Biu Biu Biu

tn s ct trn Pareto

Biu ng Biu tn s Histogram v ogive Biu Stem-andleaf Biu phn tn

Bng v th cho bin phn loiD liu phn loi

Biu din theo bng

Biu din bng th

Bng tn s

Biu ct

Biu trn

th pareto

Bng tn sTng hp d liu phn loi V d: D liu v bnh nhnKhoa nhn iu tr Tim mch Cp cu K thut cao Sn Phu thut (Bin phn loi) S bnh 1,052 2,245 340 552 4,630

Biu ct v trnp

Biu ct v Biu trn thng c s dng biu din bin nh tnh (phn loi) Chiu cao ca ct hoc ln ca cung trn biu din tn s hoc phn trm ca tng thnh phn.

p

Biu ct V dKhoa iu tr bnh nhn Tim mch Cp cu K thut cao S n Phu thut S 1,052 2,245 340 552 4,630

S bnh nhn12 10 8 6 4 2 0

Biu trn V dKhoa iu tr S % Tng bnh nhn cng 11.93 25.46 3.86 6.26 52.50

Tim mch 1,052 Cp cu 2,245 K thut cao 340 Sn 552 Phu thut 4,630

S bnh nhn

M t bin s bng thD liu s

Tn s v phn phi tch lu

Stem-&-Leaf

Histogram

Ogive

Phn b tn sp

Th no l mt phn b tn s?n n n

Mt phn b tn s l mt danh sch hoc bng cha cc nhm c chia khong(phn loi hoc phm vi m d liu lt vo) v tn s tng ng vi d liu bn trong tng khong vi mi khong hoc phn loi.

Chia khong v s khong chiap p

Chiu rng ca mi khong phi bng nhau. Xc nh chiu rng ca mi khong bng

p p

t nht 5 khong nhng khng nhiu hn 15-20 khong. Cc khong khng trng nhau.

Phn b tn sV d: o nhit ca 20 ngy ma ng c nhit cao c chn ngu nhin.24, 35, 17, 21, 24, 37, 26, 46, 58, 30, 32, 13, 12, 38, 41, 43, 44, 27, 53, 27

Phn b tn sp58

Sp xp d liu theo th t tng dn12, 13, 17, 21, 24, 24, 26, 27, 27, 30, 32, 35, 37, 38, 41, 43, 44, 46, 53,

p p p p p

Xc nh min: 58 12 = 46 Chn s khong: 5 (thng thng chn t 5 n 15) Chiu rng ca mi khong: 10 (lm trn 46/5) Xc nh bin ca mi khong: [10,20), [20,30), , [60, 70). m s phn t nm trong mi khong tng ng.

Phn b tn sD liu c sp xp:

12, 13, 17, 21, 24, 24, 26, 27, 27, 30, 32, 35, 37, 38, 41, 43, 44, 46, 53, 58

Khong [10, 20) [20, 30) [30, 40) [40, 50) [50, 60) 3 6 5 4 2

Tn s .15

Tn s quan h 15 .30 .25 .20 .10

% tch lu

30 25 20 10

Tng cng

20

1.00

100

Histogramp p

p p

Biu biu din s liu theo phn b tn s gi l histogram. Trc ngang biu din gi tr ca cc khong chia. Trc ng biu din tn s, tn s quan h hoc phn trm. Cc ct vi chiu cao thch hp biu din s quan st bn trong mt khong.

HistogramKhong [10, [20, [30, [40, [50, 20) 30) 40) 50) 60) Tn s 3 6 5 4 2

0

10

20

30

40

50

60

70

(khng ckhong cch gia cc ct)

Dng iu phn phip

Dng iu ca phn phi c gi l i xng nu cc gi tr quan st cn bng, hoc phn b xung quan trung tm.

Dng iu phn phip

Dng iu phn phi gi l bt i xng nu gi tr quan st khng phn b xung quanh trung tm.

Biu Stem & Leafp

Mt dng biu n gin dng nhn dng phn phi t d liu.

PHNG PHP: chia d liu thnh hai thnh phn gm cc ch s dn u (stem) v cc ch s ui (leaf).

V dD liu c sp xp:21, 24, 24, 26, 27, 27, 30, 32, 38, 41

p

S dng ch s hng chc lm stemStem Leafn n

21 c ghi l 38 c ghi l

2 3

1 8

V dp

S dng ch s hng trm lm stem:n

Lm trn ch s hng chc lm leafStemp p p p

Leaf 1 8 2

613 c ghi l 776 c ghi l 1224 c ghi l

6 7 12

V dp

S dng ch s hng trm lm stem:n

Biu stem & leaf hon chnh nh sauStem Leaves136 2258 346699 13368 356 47 2 6 7 8 9 10 11 12

D liu: 613, 632, 658, 717, 722, 750, 776, 827, 841, 859, 863, 891, 894, 906, 928, 933, 955, 982, 1034, 1047,1056, 1140,

1169, 1224

M t d liu sM t d liu s

tp trung Trung bnh Trung v Mode

bin thin Min d liu Min phn v Phng sai lch tiu chun H s bin thin

o tp trung ca d liuTng quan tp trung

K vng

Trung v

Mode

Gi tr trung bnh

im chnh gia ca d liu c sp xp theo hng

Gi tr quan st thng gp nht

Trung bnhp

Trung bnh l gi tri thng c s dng o mc tp trung ca d liu.n

Vi mt tng th c N gi tr:Cc gi tr ca tng th S phn t ca tng th

n

Vi mt mu c n:Cc gi tr quan trc C mu

Trung bnhp p

o tp trung B nh hng bi nhng im ngoi lai (outliers).

0 1

2

3

4

5

6

7

8

9

10

0 1

2

3

4

5

6

7

8

9

10

Trung bnh = 3

Trung bnh = 4

Trung vp

Trong mt danh sch c th t, trung v l im chnh gia(50% bn trn, 50% bn di)2 3 4 5 6 7 8 9 10 0 1 2 3 4 5 6 7 8 9 10

0 1

Trung v = 3

Trung v = 3

p

Khng b nh hng bi cc im outliers.

Xc nh trung vp

V tr ca trung v:

n n

Nu s gi tr quan trc l, trung v l im chnh gia. Nu s gi tr quan trc chn, trung v l trung bnh ca hai gi tr chnh gia.

p

Lu rng

khng phi l gi tr ca trung v, n

ch l v tr ca trung v trong d liu c sp xp.

Modep p p p p

L mt i lng o tp trung. L gi tr thng xy ra nht. Khng b nh hng bi cc im ngoi lai. C th s dng cho c d liu s v d liu phn loi. C th khng tn ti mode hoc c nhiu mode.

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

0 1 2 3 4 5 6

Khng c mode Mode = 9

Dng iu ca phn phip p

M t d liu phn b nh th no o ca dng iu (shape)n

i xng (Symmetric) hay bt i xng (skewed)

LeftMean < SkewedMedian

Symmetri Mean = cMedian

RightSkewed Median Sai s cng nh. Ch : khi n = 1 -> .

(1) C mu (n)

(2) bin thin ca tng th ( ) cng ln -> Sai s cng ln.

Phn phi mu ca trung bnhp p p

Theo nh l gii hn trung tm: phn phi ca trung bnh mu s hi t v phn phi chun khi n tin ra v cng. (*) Khng nh trn ng ngay c khi mu c chn t tng th khng phi l phn phi chun. Chn c mu nh th no?n n

n

Nu tng th c phn phi chun, mi n u tha. Nu tng th khng c phn phi chun, nhng c phn phi i xng, c mu nh c th chp nhn c. Nu tng th khng c phn phi chun v phn phi bt i xng, n phi ln, thng thng n 30.

Phn phi mu ca phng sai

Phn phi mu ca t lP = T l ca tng th c c tnh cn nghin cu. T l mu l mt c lng ca t l P:

0

1c th xp x c phn phi

Phn phi ca chun.

Phn phi mu c