Transcript

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

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

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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

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

.

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

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

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

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

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

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

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

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.

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


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