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1 Slide © 2008 Thomson South-Western. All Rights Reserved Slides by JOHN LOUCKS St. Edward’s University 2 Slide © 2008 Thomson South-Western. All Rights Reserved Chapter 13, Part A Experimental Design and Analysis of Variance Introduction to Experimental Design and Analysis of Variance Analysis of Variance and the Completely Randomized Design Multiple Comparison Procedures 3 Slide © 2008 Thomson South-Western. All Rights Reserved Statistical studies can be classified as being either experimental or observational. In an experimental study , one or more factors are controlled so that data can be obtained about how the factors influence the variables of interest. In an observational study , no attempt is made to control the factors. Cause-and-effect relationships are easier to establish in experimental studies than in observational studies. An Introduction to Experimental Design and Analysis of Variance Analysis of variance (ANOVA) can be used to analyze the data obtained from experimental or observational studies. 4 Slide © 2008 Thomson South-Western. All Rights Reserved An Introduction to Experimental Design and Analysis of Variance In this chapter three types of experimental designs are introduced. a completely randomized design a randomized block design a factorial experiment
12

•a completely randomized design An Introduction to ...wilderemail.com/Stats/272docs/DEWChpt13A.pdf · 1 Slide © 2008 Thomson South-Western. All Rights Reserved Slides by JOHN LOUCKS

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Page 1: •a completely randomized design An Introduction to ...wilderemail.com/Stats/272docs/DEWChpt13A.pdf · 1 Slide © 2008 Thomson South-Western. All Rights Reserved Slides by JOHN LOUCKS

1S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

Slides by

JOHN

LOUCKS

St. Edward’s

University

2S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

Ch

apte

r 13

, Par

t A

Ex

per

imen

tal

Des

ign

an

d A

nal

ysi

s o

f V

aria

nce

�In

tro

du

ctio

n t

o E

xp

erim

enta

l D

esig

n

and

An

aly

sis

of

Var

ian

ce

�A

nal

ysi

s o

f V

aria

nce

and

th

e C

om

ple

tely

Ran

do

miz

ed D

esig

n

�M

ult

iple

Co

mp

aris

on

Pro

ced

ure

s

3S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

�S

tati

stic

al s

tud

ies

can

be

clas

sifi

ed a

s b

ein

g e

ith

er

exp

erim

enta

l o

r o

bse

rvat

ion

al.

�In

an

ex

per

imen

tal

stu

dy

, on

e o

r m

ore

fac

tors

are

co

ntr

oll

ed s

o t

ha

t d

ata

can

be

ob

tain

ed a

bo

ut

ho

w t

he

fact

ors

in

flu

ence

th

e v

aria

ble

s o

f in

tere

st.

�In

an

ob

serv

atio

na

l st

ud

y, n

o a

ttem

pt

is m

ade

to

con

tro

l th

e fa

cto

rs.

�C

ause

-an

d-e

ffec

t re

lati

on

ship

sar

e ea

sier

to

est

abli

sh

in e

xp

erim

enta

l st

ud

ies

than

in

ob

serv

atio

nal

stu

die

s.

An

In

tro

du

ctio

n t

o E

xp

erim

enta

l D

esig

nan

d A

nal

ysi

s o

f V

ari

ance

�A

nal

ysi

s o

f v

aria

nce

(A

NO

VA

) ca

n b

e u

sed

to

an

aly

ze

the

da

ta o

bta

ined

fro

m e

xp

erim

enta

l o

r o

bse

rvat

ion

al

stu

die

s.

4S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

An

In

tro

du

ctio

n t

o E

xp

erim

enta

l D

esig

nan

d A

nal

ysi

s o

f V

ari

ance

�In

th

is c

ha

pte

r th

ree

typ

es o

f ex

per

imen

tal

des

ign

s ar

e in

tro

du

ced

.

•a

com

ple

tely

ra

nd

om

ized

des

ign

•a

ran

do

miz

ed b

lock

des

ign

•a

fact

ori

al e

xp

erim

ent

Page 2: •a completely randomized design An Introduction to ...wilderemail.com/Stats/272docs/DEWChpt13A.pdf · 1 Slide © 2008 Thomson South-Western. All Rights Reserved Slides by JOHN LOUCKS

5S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

An

In

tro

du

ctio

n t

o E

xp

erim

enta

l D

esig

nan

d A

nal

ysi

s o

f V

ari

ance

�A

fac

tor

is a

var

iab

le t

hat

th

e ex

per

imen

ter

has

se

lect

ed f

or

inv

esti

ga

tio

n.

�A

tre

atm

ent

is a

lev

el o

f a

fact

or.

�E

xp

erim

enta

l u

nit

sar

e th

e o

bje

cts

of

inte

rest

in

th

e ex

per

imen

t.

�A

co

mp

lete

ly r

an

do

miz

ed d

esig

nis

an

ex

per

imen

tal

des

ign

in

wh

ich

th

e tr

eatm

ents

are

ran

do

mly

as

sig

ned

to

th

e ex

per

imen

tal

un

its.

6S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

An

aly

sis

of

Var

ian

ce: A

Co

nce

ptu

al O

ver

vie

w

An

aly

sis

of

Var

ian

ce(A

NO

VA

) ca

n b

e u

sed

to

tes

tfo

r th

e eq

ual

ity

of

thre

e o

r m

ore

po

pu

lati

on

mea

ns.

Dat

a o

bta

ined

fro

m o

bse

rvat

ion

al o

r ex

per

imen

tal

stu

die

s ca

n b

e u

sed

fo

r th

e an

aly

sis.

We

wan

t to

use

th

e sa

mp

le r

esu

lts

to t

est

the

foll

ow

ing

hy

po

thes

es:

H0:

µ1

= µ

2 = µ

3 = .

. .

= µ

k

Ha:

No

t al

l p

op

ula

tio

n m

ean

s ar

e eq

ual

7S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

H0:

µ1

= µ

2 = µ

3 = .

. .

= µ

k

Ha:

No

t al

l p

op

ula

tio

n m

ean

s ar

e eq

ual

If H

0is

rej

ecte

d, w

e ca

nn

ot

con

clu

de

that

all

po

pu

lati

on

mea

ns

are

dif

fere

nt.

Rej

ecti

ng

H0

mea

ns

that

at

leas

t tw

o p

op

ula

tio

n

mea

ns

hav

e d

iffe

ren

t v

alu

es.

An

aly

sis

of

Var

ian

ce: A

Co

nce

ptu

al O

ver

vie

w

8S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

Fo

r ea

ch p

op

ula

tio

n,

the

resp

on

se (

dep

end

ent)

var

iab

le i

s n

orm

all

y d

istr

ibu

ted

.

Th

e v

aria

nce

of

the

resp

on

se v

aria

ble

, den

ote

d σ 2

,is

th

e sa

me

for

all

of

the

po

pu

lati

on

s.

Th

e o

bse

rvat

ion

s m

ust

be

ind

epen

den

t.

�A

ssu

mp

tio

ns

for

An

aly

sis

of

Var

ian

ce

An

aly

sis

of

Var

ian

ce: A

Co

nce

ptu

al O

ver

vie

w

Page 3: •a completely randomized design An Introduction to ...wilderemail.com/Stats/272docs/DEWChpt13A.pdf · 1 Slide © 2008 Thomson South-Western. All Rights Reserved Slides by JOHN LOUCKS

9S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

�S

amp

lin

g D

istr

ibu

tio

n o

f

Giv

en H

0is

Tru

ex µ

1x 1x

3x 3x

2x 2x

Sam

ple

mea

ns

are

clo

se t

og

eth

erb

ecau

se t

her

e is

on

lyo

ne

sam

pli

ng

dis

trib

uti

on

wh

en H

0is

tru

e.

22 x

nσσ

=2

2 xnσ

σ=

An

aly

sis

of

Var

ian

ce: A

Co

nce

ptu

al O

ver

vie

w

10S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

�S

amp

lin

g D

istr

ibu

tio

n o

f

Giv

en H

0is

Fal

sex

µ3

1x 1x

2x 2x

3x 3x

µ1

µ2

Sam

ple

mea

ns

com

e fr

om

dif

fere

nt

sam

pli

ng

dis

trib

uti

on

san

d a

re n

ot

as c

lose

to

get

her

wh

en H

0is

fal

se.

An

aly

sis

of

Var

ian

ce: A

Co

nce

ptu

al O

ver

vie

w

11S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

An

aly

sis

of

Var

ian

ce

�B

etw

een

-Tre

atm

ents

Est

imat

e o

f P

op

ula

tio

n V

ari

an

ce

�W

ith

in-T

reat

men

ts E

stim

ate

of

Po

pu

lati

on

Var

ian

ce

�C

om

par

ing

th

e V

aria

nce

Est

imat

es: T

he F T

est

�A

NO

VA

Tab

le

12S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

2

1

()

MS

TR

1

k

jj

j

nx

x

k

=

=−

Bet

wee

n-T

reat

men

ts E

stim

ate

of

Po

pu

lati

on

Var

ian

ce σ 2

Den

om

ina

tor

is t

he

deg

rees

of

free

do

mas

soci

ated

wit

h S

ST

R

Nu

mer

ato

r is

cal

led

the

sum

of

squ

ares

du

eto

tre

atm

ents

(SS

TR

)

�T

he

esti

ma

te o

f σ 2

bas

ed o

n t

he

var

iati

on

of

the

sam

ple

mea

ns

is c

alle

d t

he

mea

n s

qu

are

du

e to

trea

tmen

tsan

d i

s d

eno

ted

by

MS

TR

.

Page 4: •a completely randomized design An Introduction to ...wilderemail.com/Stats/272docs/DEWChpt13A.pdf · 1 Slide © 2008 Thomson South-Western. All Rights Reserved Slides by JOHN LOUCKS

13S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

�T

he

esti

ma

te o

f σ 2

bas

ed o

n t

he

var

iati

on

of

the

sam

ple

ob

serv

atio

ns

wit

hin

eac

h s

amp

le i

s ca

lled

th

e m

ean

sq

uar

e er

ror

and

is

den

ote

d b

y M

SE

.

Wit

hin

-Tre

atm

ents

Est

imat

eo

f P

op

ula

tio

n V

aria

nce

σ 2

Den

om

ina

tor

is t

he

deg

rees

of

free

do

mas

soci

ated

wit

h S

SE

Nu

mer

ato

r is

cal

led

the

sum

of

squ

ares

du

e to

err

or

(SS

E)

MS

E=

−∑

=

()

ns

nk

jj

jk

T

12

1M

SE=

−∑

=

()

ns

nk

jj

jk

T

12

1

14S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

Co

mp

arin

g t

he

Var

ian

ce E

stim

ates

: Th

e F

Tes

t

�If

th

e n

ull

hy

po

thes

is i

s tr

ue

and

th

e A

NO

VA

assu

mp

tio

ns

are

val

id, t

he

sam

pli

ng

dis

trib

uti

on

of

MS

TR

/M

SE

is

an F

dis

trib

uti

on

wit

h M

ST

R d

.f.

equ

al t

o k

-1

and

MS

E d

.f. e

qu

al t

o n

T-k.

�If

th

e m

ean

s o

f th

e k

po

pu

lati

on

s ar

e n

ot

equ

al, t

he

val

ue

of

MS

TR

/M

SE

wil

l b

e in

flat

ed b

ecau

se M

ST

Ro

ver

esti

mat

es σ 2

.

�H

ence

, we

wil

l re

ject

H0

if t

he

resu

ltin

g v

alu

e o

fM

ST

R/

MS

E a

pp

ears

to

be

too

lar

ge

to h

av

e b

een

sele

cted

at

ran

do

m f

rom

th

e ap

pro

pri

ate F

dis

trib

uti

on

.

15S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

�S

amp

lin

g D

istr

ibu

tio

n o

f M

ST

R/

MS

E

Do

No

t R

ejec

t H

0

Rej

ect H

0

MS

TR

/M

SE

Cri

tica

l V

alu

e

Sam

pli

ng

Dis

trib

uti

on

of

MS

TR

/M

SE

α

Co

mp

arin

g t

he

Var

ian

ce E

stim

ates

: Th

e F

Tes

t

16S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

MS

TR

SS

TR

-=k

1M

ST

RS

ST

R

-=k

1

MS

ES

SE -

=n

kT

MS

ES

SE -

=n

kT

MS

TR

MS

E

MS

TR

MS

E

So

urc

e o

fV

aria

tio

nS

um

of

Sq

uar

esD

egre

es o

fF

reed

om

Mea

nS

qu

are

F

Tre

atm

ents

Err

or

To

tal

k-

1

nT

-1

SS

TR

SS

E

SS

T

nT

-k

SS

T i

s p

arti

tio

ned

into

SS

TR

an

d S

SE

.

SS

T’s

deg

rees

of

free

do

m

(d.f

.) a

re p

arti

tio

ned

in

to

SS

TR

’sd

.f. a

nd

SS

E’s

d.f

.

AN

OV

A T

able

p-V

alu

e

Page 5: •a completely randomized design An Introduction to ...wilderemail.com/Stats/272docs/DEWChpt13A.pdf · 1 Slide © 2008 Thomson South-Western. All Rights Reserved Slides by JOHN LOUCKS

17S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

AN

OV

A T

able

SS

T d

ivid

ed b

y i

ts d

egre

es o

f fr

eed

om

nT

–1

is t

he

ov

eral

l sa

mp

le v

aria

nce

th

at

wo

uld

be

ob

tain

ed i

f w

etr

eate

d t

he

enti

re s

et o

f o

bse

rvat

ion

s as

on

e d

ata

set.

Wit

h t

he

enti

re d

ata

set

as o

ne

sam

ple

, th

e fo

rmu

lafo

r co

mp

uti

ng

th

e to

tal

sum

of

squ

ares

, SS

T, i

s:

2

11

SS

T(

)S

ST

RS

SE

jn

k

ijj

i

xx

==

=−

=+

∑∑

18S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

AN

OV

A T

able

AN

OV

A c

an b

e v

iew

ed a

s th

e p

roce

ss o

f p

arti

tio

nin

gth

e to

tal

sum

of

squ

ares

an

d t

he

deg

rees

of

free

do

min

to t

hei

r co

rres

po

nd

ing

so

urc

es: t

reat

men

ts a

nd

err

or.

Div

idin

g t

he

sum

of

squ

ares

by

th

e ap

pro

pri

ate

deg

rees

of

free

do

m p

rov

ides

th

e v

aria

nce

est

ima

tes

and

th

e F

val

ue

use

d t

o t

est

the

hy

po

thes

is o

f eq

ual

po

pu

lati

on

mea

ns.

19S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

Tes

t fo

r th

e E

qu

alit

y o

f k

Po

pu

lati

on

Mea

ns

F=

MS

TR

/M

SE

H0:

µ1

= µ

2 = µ

3 = .

. .

= µ

k

Ha:

No

t al

l p

op

ula

tio

n m

ean

s ar

e eq

ual

�H

yp

oth

eses

�T

est

Sta

tist

ic

20S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

Tes

t fo

r th

e E

qu

alit

y o

f k

Po

pu

lati

on

Mea

ns

�R

ejec

tio

n R

ule

wh

ere

the

val

ue

of Fα is

bas

ed o

n a

nF

dis

trib

uti

on

wit

h k

-1

nu

mer

ato

r d

.f.

and

nT

-k

den

om

ina

tor

d.f

.

Rej

ect H

0if

p-v

alu

e <α

p-v

alu

e A

pp

roac

h:

Cri

tica

l V

alu

e A

pp

roac

h:

Rej

ect H

0if

F>Fα

Page 6: •a completely randomized design An Introduction to ...wilderemail.com/Stats/272docs/DEWChpt13A.pdf · 1 Slide © 2008 Thomson South-Western. All Rights Reserved Slides by JOHN LOUCKS

21S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

Au

toS

hin

e, I

nc.

is

con

sid

erin

g m

ark

etin

g a

lo

ng

-

last

ing

car

wax

. T

hre

e d

iffe

ren

t w

axes

(T

yp

e 1,

Ty

pe

2,

and

Ty

pe

3)

hav

e b

een

dev

elo

ped

.

�E

xam

ple

: A

uto

Sh

ine,

In

c.

In o

rder

to

tes

t th

e d

ura

bil

ity

of

thes

e w

axes

, 5 n

ew c

ars

wer

e

wax

ed w

ith

Ty

pe

1, 5

wit

h T

yp

e

2, a

nd

5 w

ith

Ty

pe

3. E

ach

car

was

th

en

rep

eate

dly

ru

n t

hro

ug

h a

n a

uto

mat

ic c

arw

ash

un

til

the

wax

co

atin

g s

ho

wed

sig

ns

of

det

erio

rati

on

.

Tes

tin

g f

or

the

Eq

ual

ity

of k

Po

pu

lati

on

Mea

ns:

A C

om

ple

tely

Ran

do

miz

ed E

xp

erim

enta

l D

esig

n

22S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

Th

e n

um

ber

of

tim

es e

ach

car

wen

t th

rou

gh

th

e

carw

ash

bef

ore

its

wax

det

erio

rate

d i

s sh

ow

n o

n t

he

nex

t sl

ide.

A

uto

Sh

ine,

In

c. m

ust

dec

ide

wh

ich

wax

to m

ark

et.

Are

th

e th

ree

wax

es

equ

ally

eff

ecti

ve?

�E

xam

ple

: A

uto

Sh

ine,

In

c.

Tes

tin

g f

or

the

Eq

ual

ity

of k

Po

pu

lati

on

Mea

ns:

A C

om

ple

tely

Ran

do

miz

ed E

xp

erim

enta

l D

esig

n

Fac

tor

. . .

C

ar w

ax

Tre

atm

ents

. .

. T

yp

e I,

Ty

pe

2, T

yp

e 3

Ex

per

imen

tal

un

its

. .

. C

ars

Res

po

nse

var

iab

le

. . .

Nu

mb

er o

f w

ash

es

23S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

1 2 3 4 5

27 30 29 28 31

33 28 31 30 30

29 28 30 32 31

Sam

ple

Mea

n

Sam

ple

Va

rian

ce

Ob

serv

atio

nW

axT

yp

e 1

Wax

Ty

pe

2W

axT

yp

e 3

2.5

3.3

2.5

29.0

30.4

30.0

Tes

tin

g f

or

the

Eq

ual

ity

of k

Po

pu

lati

on

Mea

ns:

A C

om

ple

tely

Ran

do

miz

ed E

xp

erim

enta

l D

esig

n

24S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

�H

yp

oth

eses

wh

ere:

µ1 =

mea

n n

um

ber

of

was

hes

usi

ng

Ty

pe

1 w

ax

µ2 =

mea

n n

um

ber

of

was

hes

usi

ng

Ty

pe

2 w

ax

µ3 =

mea

n n

um

ber

of

was

hes

usi

ng

Ty

pe

3 w

ax

H0:

µ1

= µ

2 = µ

3

Ha:

No

t al

l th

e m

ean

s ar

e eq

ual

Tes

tin

g f

or

the

Eq

ual

ity

of k

Po

pu

lati

on

Mea

ns:

A C

om

ple

tely

Ran

do

miz

ed E

xp

erim

enta

l D

esig

n

Page 7: •a completely randomized design An Introduction to ...wilderemail.com/Stats/272docs/DEWChpt13A.pdf · 1 Slide © 2008 Thomson South-Western. All Rights Reserved Slides by JOHN LOUCKS

25S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

Bec

ause

th

e sa

mp

le s

izes

are

all

eq

ual

:

MS

E =

33.

2/(1

5 -

3) =

2.7

7

MS

TR

= 5

.2/

(3 -

1) =

2.6

SS

E =

4(2

.5)

+ 4

(3.3

) +

4(2

.5)

= 3

3.2

SS

TR

= 5

(29

–29.

8)2

+ 5

(30.

4–2

9.8)

2+

5(3

0–29

.8)2

= 5

.2

�M

ean

Sq

ua

re E

rro

r

�M

ean

Sq

ua

re B

etw

een

Tre

atm

ents

=+

+1

23

()/

3x

xxx

=+

+1

23

()/

3x

xxx

= (

29 +

30.

4 +

30)

/3

= 2

9.8

Tes

tin

g f

or

the

Eq

ual

ity

of k

Po

pu

lati

on

Mea

ns:

A C

om

ple

tely

Ran

do

miz

ed E

xp

erim

enta

l D

esig

n

26S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

�R

ejec

tio

n R

ule

wh

ere F

.05

= 3

.89

is b

ased

on

an

Fd

istr

ibu

tio

nw

ith

2 n

um

erat

or

deg

rees

of

free

do

m a

nd

12

den

om

inat

or

deg

rees

of

free

do

m

p-V

alu

e A

pp

roac

h:

Rej

ect H

0if

p-v

alu

e <

.05

Cri

tica

l V

alu

e A

pp

roac

h:

Rej

ect H

0if

F>

3.89

Tes

tin

g f

or

the

Eq

ual

ity

of k

Po

pu

lati

on

Mea

ns:

A C

om

ple

tely

Ran

do

miz

ed E

xp

erim

enta

l D

esig

n

27S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

�T

est

Sta

tist

ic

Th

ere

is i

nsu

ffic

ien

t ev

iden

ce t

o c

on

clu

de

that

the

mea

n n

um

ber

of

was

hes

fo

r th

e th

ree

wax

typ

es a

re n

ot

all

the

sam

e.

�C

on

clu

sio

nF =

MS

TR

/M

SE

= 2

.60/

2.77

= .9

39

Th

e p-

val

ue

is g

reat

er t

ha

n .1

0, w

her

e F

= 2

.81.

(Ex

cel

pro

vid

es a

p-v

alu

e o

f .4

2.)

Th

eref

ore

, we

can

no

t re

ject

H0.

Tes

tin

g f

or

the

Eq

ual

ity

of k

Po

pu

lati

on

Mea

ns:

A C

om

ple

tely

Ran

do

miz

ed E

xp

erim

enta

l D

esig

n

28S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

So

urc

e o

fV

aria

tio

nS

um

of

Sq

uar

esD

egre

es o

fF

reed

om

Mea

nS

qu

ares

F

Tre

atm

ents

Err

or

To

tal

2 14

5.2

33.2

38.4

12

2.60

2.77

.939

�A

NO

VA

Tab

le

Tes

tin

g f

or

the

Eq

ual

ity

of k

Po

pu

lati

on

Mea

ns:

A C

om

ple

tely

Ran

do

miz

ed E

xp

erim

enta

l D

esig

n

p-V

alu

e

.42

Page 8: •a completely randomized design An Introduction to ...wilderemail.com/Stats/272docs/DEWChpt13A.pdf · 1 Slide © 2008 Thomson South-Western. All Rights Reserved Slides by JOHN LOUCKS

29S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

�E

xam

ple

: R

eed

Man

ufa

ctu

rin

g

Jan

et R

eed

wo

uld

lik

e to

kn

ow

if

ther

e is

an

y s

ign

ific

ant

dif

fere

nce

in

the

mea

n n

um

ber

of

ho

urs

wo

rked

per

wee

k f

or

the

dep

artm

ent

ma

nag

ers

at h

er t

hre

e m

anu

fact

uri

ng

pla

nts

(in

Bu

ffal

o, P

itts

bu

rgh

, an

d D

etro

it).

An

Fte

st w

ill

be

con

du

cted

usi

ng

α=

.05.

Tes

tin

g f

or

the

Eq

ual

ity

of k

Po

pu

lati

on

Mea

ns:

An

Ob

serv

atio

nal

Stu

dy

30S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

�E

xam

ple

: R

eed

Man

ufa

ctu

rin

g

A s

imp

le r

and

om

sam

ple

of

fiv

e

man

ager

s fr

om

eac

h o

f th

e th

ree

pla

nts

was

tak

en a

nd

th

e n

um

ber

of

ho

urs

wo

rked

by

eac

h m

ana

ger

in

th

e

pre

vio

us

wee

k i

s sh

ow

n o

n t

he

nex

t

slid

e.

Tes

tin

g f

or

the

Eq

ual

ity

of k

Po

pu

lati

on

Mea

ns:

An

Ob

serv

atio

nal

Stu

dy

Fac

tor

. . .

M

anu

fact

uri

ng

pla

nt

Tre

atm

ents

. .

. B

uff

alo

, Pit

tsb

urg

h, D

etro

it

Ex

per

imen

tal

un

its

. .

. M

ana

ger

s

Res

po

nse

var

iab

le

. . .

Nu

mb

er o

f h

ou

rs w

ork

ed

31S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

1 2 3 4 5

48 54 57 54 62

73 63 66 64 74

51 63 61 54 56

Pla

nt

1B

uff

alo

Pla

nt

2P

itts

bu

rgh

Pla

nt

3D

etro

itO

bse

rvat

ion

Sam

ple

Mea

n

Sam

ple

Va

rian

ce

5568

57

26.0

26.5

24.5

Tes

tin

g f

or

the

Eq

ual

ity

of k

Po

pu

lati

on

Mea

ns:

An

Ob

serv

atio

nal

Stu

dy

32S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

H0:

µ 1 = µ 2 = µ 3

Ha:

No

t al

l th

e m

ean

s ar

e eq

ual

wh

ere:

µ 1

= m

ean

nu

mb

er o

f h

ou

rs w

ork

ed p

erw

eek

by

th

e m

ana

ger

s at

Pla

nt

1µ 2

= m

ean

nu

mb

er o

f h

ou

rs w

ork

ed p

erw

eek

by

th

e m

anag

ers

at

Pla

nt

2 µ 3

= m

ean

nu

mb

er o

f h

ou

rs w

ork

ed p

erw

eek

by

th

e m

anag

ers

at

Pla

nt

3

1. D

evel

op

th

e h

yp

oth

eses

.

�p

-Val

ue

and

Cri

tica

l V

alu

e A

pp

roac

hes

Tes

tin

g f

or

the

Eq

ual

ity

of k

Po

pu

lati

on

Mea

ns:

An

Ob

serv

atio

nal

Stu

dy

Page 9: •a completely randomized design An Introduction to ...wilderemail.com/Stats/272docs/DEWChpt13A.pdf · 1 Slide © 2008 Thomson South-Western. All Rights Reserved Slides by JOHN LOUCKS

33S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

2. S

pec

ify

th

e le

vel

of

sig

nif

ican

ce.

α =

.05

�p

-Val

ue

and

Cri

tica

l V

alu

e A

pp

roac

hes

3. C

om

pu

te t

he

val

ue

of

the

test

sta

tist

ic.

MS

TR

= 4

90/

(3 -

1) =

2

45

SS

TR

= 5

(55

-60

)2+

5(6

8 -

60)2

+ 5

(57

-60

)2=

490

= (

55 +

68

+ 5

7)/

3 =

60

xx(Sam

ple

siz

es a

re a

ll e

qu

al.)

Mea

n S

qu

are

Du

e to

Tre

atm

ents

Tes

tin

g f

or

the

Eq

ual

ity

of k

Po

pu

lati

on

Mea

ns:

An

Ob

serv

atio

nal

Stu

dy

34S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

3. C

om

pu

te t

he

val

ue

of

the

test

sta

tist

ic.

MS

E =

308

/(1

5 -

3) =

2

5.66

7

SS

E =

4(2

6.0)

+ 4

(26.

5) +

4(2

4.5)

= 3

08

Mea

n S

qu

are

Du

e to

Err

or

(co

n’t

.)

F=

MS

TR

/M

SE

= 2

45/

25.6

67 =

9.

55

�p

-Val

ue

and

Cri

tica

l V

alu

e A

pp

roac

hes

Tes

tin

g f

or

the

Eq

ual

ity

of k

Po

pu

lati

on

Mea

ns:

An

Ob

serv

atio

nal

Stu

dy

35S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

Tre

atm

ent

Err

or

To

tal

490

308

798

2 12 14

245

25.6

67

So

urc

e o

fV

aria

tio

nS

um

of

Sq

uar

esD

egre

es o

fF

reed

om

Mea

nS

qu

are

9.55F

�A

NO

VA

Tab

le

Tes

tin

g f

or

the

Eq

ual

ity

of k

Po

pu

lati

on

Mea

ns:

An

Ob

serv

atio

nal

Stu

dy

p-V

alu

e

.003

3

36S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

5. D

eter

min

e w

het

her

to

rej

ect H

0.

We

hav

e su

ffic

ien

t ev

iden

ce t

o c

on

clu

de

that

th

e m

ean

nu

mb

er o

f h

ou

rs w

ork

ed p

er w

eek

by

d

epar

tmen

t m

ana

ger

s is

no

t th

e sa

me

at a

ll 3

pla

nt.

Th

e p-

val

ue

<.0

5,so

we

reje

ct H

0.

Wit

h 2

nu

mer

ato

r d

.f. a

nd

12

den

om

ina

tor

d.f

.,th

e p-

val

ue

is .0

1 fo

r F

= 6

.93.

T

her

efo

re, t

he

p-v

alu

e is

les

s th

an .0

1 f

or F

= 9

.55.

�p

–Val

ue

Ap

pro

ach

4. C

om

pu

te t

he p

–va

lue.

Tes

tin

g f

or

the

Eq

ual

ity

of k

Po

pu

lati

on

Mea

ns:

An

Ob

serv

atio

nal

Stu

dy

Page 10: •a completely randomized design An Introduction to ...wilderemail.com/Stats/272docs/DEWChpt13A.pdf · 1 Slide © 2008 Thomson South-Western. All Rights Reserved Slides by JOHN LOUCKS

37S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

5. D

eter

min

e w

het

her

to

rej

ect H

0.

Bec

ause

F=

9.5

5 >

3.89

, we

reje

ct H

0.

�C

riti

cal

Val

ue

Ap

pro

ach

4. D

eter

min

e th

e cr

itic

al v

alu

e an

d r

ejec

tio

n r

ule

.

Rej

ect H

0if

F>

3.89

We

hav

e su

ffic

ien

t ev

iden

ce t

o c

on

clu

de

that

th

e m

ean

nu

mb

er o

f h

ou

rs w

ork

ed p

er w

eek

by

d

epar

tmen

t m

ana

ger

s is

no

t th

e sa

me

at a

ll 3

pla

nt.

Bas

ed o

n a

n F

dis

trib

uti

on

wit

h 2

nu

mer

ato

rd

.f. a

nd

12

den

om

inat

or

d.f

., F

.05

= 3

.89.

Tes

tin

g f

or

the

Eq

ual

ity

of k

Po

pu

lati

on

Mea

ns:

An

Ob

serv

atio

nal

Stu

dy

38S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

Mu

ltip

le C

om

par

iso

n P

roce

du

res

�S

up

po

se t

hat

an

aly

sis

of

var

ian

ce h

as p

rov

ided

st

atis

tica

l ev

iden

ce t

o r

ejec

t th

e n

ull

hy

po

thes

is o

f eq

ual

po

pu

lati

on

mea

ns.

�F

ish

er’s

lea

st s

ign

ific

an

t d

iffe

ren

ce (

LS

D)

pro

ced

ure

ca

n b

e u

sed

to

det

erm

ine

wh

ere

the

dif

fere

nce

s o

ccu

r.

39S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

Fis

her

’s L

SD

Pro

ced

ure

11

MS

E(

)

ij

ij

xx

t

nn

−=

+

�T

est

Sta

tist

ic

�H

yp

oth

eses

µµ

−0

: i

jH

µµ

≠:

ai

jH

40S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

Fis

her

’s L

SD

Pro

ced

ure

wh

ere

the

val

ue

of t a

/2 is

bas

ed o

n a

td

istr

ibu

tio

n w

ith

nT

-k

deg

rees

of

free

do

m.

�R

ejec

tio

n R

ule

Rej

ect H

0if

p-v

alu

e <α

p-v

alu

e A

pp

roac

h:

Cri

tica

l V

alu

e A

pp

roac

h:

Rej

ect H

0if

t<

-t a

/2 o

r t

> ta/

2

Page 11: •a completely randomized design An Introduction to ...wilderemail.com/Stats/272docs/DEWChpt13A.pdf · 1 Slide © 2008 Thomson South-Western. All Rights Reserved Slides by JOHN LOUCKS

41S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

�T

est

Sta

tist

ic

Fis

her

’s L

SD

Pro

ced

ure

Bas

ed o

n t

he

Tes

t S

tati

stic

xi-xj

__

/2

11

LS

DM

SE

()

ij

tn

=+

wh

ere

−i

jx

x

Rej

ect H

0if

> L

SD

−i

jx

x

�H

yp

oth

eses

�R

ejec

tio

n R

ule

µµ

−0

: i

jH

µµ

≠:

ai

jH

42S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

Fis

her

’s L

SD

Pro

ced

ure

Bas

ed o

n t

he

Tes

t S

tati

stic

xi-xj

�E

xam

ple

: R

eed

Man

ufa

ctu

rin

g

Rec

all

that

Jan

et R

eed

wan

ts t

o k

no

w

if t

her

e is

an

y s

ign

ific

an

t d

iffe

ren

ce i

n

the

mea

n n

um

ber

of

ho

urs

wo

rked

per

wee

k f

or

the

dep

artm

ent

ma

nag

ers

at h

er t

hre

e m

anu

fact

uri

ng

pla

nts

.

An

aly

sis

of

var

ian

ce h

as p

rov

ided

stat

isti

cal

evid

ence

to

rej

ect

the

nu

ll

hy

po

thes

is o

f eq

ual

po

pu

lati

on

mea

ns.

Fis

her

’s l

east

sig

nif

ica

nt

dif

fere

nce

(L

SD

) p

roce

du

re

can

be

use

d t

o d

eter

min

e w

her

e th

e d

iffe

ren

ces

occ

ur.

43S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

Fo

r α

= .0

5 an

d n

T-k

= 1

5 –

3 =

12

deg

rees

of

free

do

m, t.0

25 =

2.1

79

LS

D=

+=

217

925

667

15

15

698

..

()

.L

SD=

+=

217

925

667

15

15

698

..

()

.

/2

11

LS

DM

SE

()

ij

tn

=+

MS

E v

alu

e w

asco

mp

ute

d e

arli

er

Fis

her

’s L

SD

Pro

ced

ure

Bas

ed o

n t

he

Tes

t S

tati

stic

xi-xj

44S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

�L

SD

fo

r P

lan

ts 1

an

d 2

Fis

her

’s L

SD

Pro

ced

ure

Bas

ed o

n t

he

Tes

t S

tati

stic

xi-xj

•C

on

clu

sio

n

•T

est

Sta

tist

ic

−1

2x

x=

|55

−68

| =

13

Rej

ect H

0if

> 6

.98

−1

2x

x

•R

ejec

tio

n R

ule

µµ

−0

12

: H

µµ

≠1

2:

aH

µµ

≠1

2:

aH

•H

yp

oth

eses

(A

)

Th

e m

ean

nu

mb

er o

f h

ou

rs w

ork

ed a

t P

lan

t 1

is

no

t eq

ual

to t

he

mea

n n

um

ber

wo

rked

at

Pla

nt

2.

Page 12: •a completely randomized design An Introduction to ...wilderemail.com/Stats/272docs/DEWChpt13A.pdf · 1 Slide © 2008 Thomson South-Western. All Rights Reserved Slides by JOHN LOUCKS

45S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

�L

SD

fo

r P

lan

ts 1

an

d 3

Fis

her

’s L

SD

Pro

ced

ure

Bas

ed o

n t

he

Tes

t S

tati

stic

xi-xj

•C

on

clu

sio

n

•T

est

Sta

tist

ic

−1

3x

x=

|55

−57

| =

2

Rej

ect H

0if

> 6

.98

−1

3x

x

•R

ejec

tio

n R

ule

µµ

−0

13

: H

µµ

≠1

3:

aH

•H

yp

oth

eses

(B

)

Th

ere

is n

o s

ign

ific

ant

dif

fere

nce

bet

wee

n t

he

mea

n

nu

mb

er o

f h

ou

rs w

ork

ed a

t P

lan

t 1

and

th

e m

ean

nu

mb

er o

f h

ou

rs w

ork

ed a

t P

lan

t 3.

46S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

�L

SD

fo

r P

lan

ts 2

an

d 3

Fis

her

’s L

SD

Pro

ced

ure

Bas

ed o

n t

he

Tes

t S

tati

stic

xi-xj

•C

on

clu

sio

n

•T

est

Sta

tist

ic

−2

3x

x=

|68

−57

| =

11

Rej

ect H

0if

> 6

.98

−2

3x

x

•R

ejec

tio

n R

ule

µµ

−0

23

: H

µµ

≠2

3:

aH

•H

yp

oth

eses

(C

)

Th

e m

ean

nu

mb

er o

f h

ou

rs w

ork

ed a

t P

lan

t 2

is

no

t eq

ual

to t

he

mea

n n

um

ber

wo

rked

at

Pla

nt

3.

47S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

�T

he

exp

erim

ent-

wis

e T

yp

e I

erro

r ra

te g

ets

larg

er f

or

pro

ble

ms

wit

h m

ore

po

pu

lati

on

s (l

arg

er k

).

Ty

pe

I E

rro

r R

ates

αE

W=

1 –

(1 –α

)(k –

1)!

�T

he

com

par

iso

n-w

ise

Ty

pe

I er

ror

rateα

ind

icat

es

the

lev

el o

f si

gn

ific

ance

ass

oci

ated

wit

h a

sin

gle

p

airw

ise

com

par

iso

n.

�T

he

exp

erim

ent-

wis

e T

yp

e I

erro

r ra

teα

EW

is t

he

pro

bab

ilit

y o

f m

akin

g a

Ty

pe

I er

ror

on

at

leas

t o

ne

of

the

(k–

1)!

pai

rwis

eco

mp

aris

on

s.

48S

lid

200

8 T

ho

mso

n S

ou

th-W

este

rn.

All

Rig

hts

Res

erv

ed

En

d o

f C

hap

ter

13, P

art

A