hw 9 - 
 Homework
Assignment
9
 Psychology
60
...

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Unformatted text preview: 
 Homework
Assignment
9
 Psychology
60
 Spring
2010
 
 
 
 General
Instructions:
 ‐ Make
sure
your
homework
has
written
on
it:
 o YOUR
NAME
 o YOUR
STUDENT
ID
 o YOUR
TA’S
NAME
(you
can
find
this
on
the
syllabus)
 
 ‐ Please
be
sure
your
homework
answers
are
LEGIBLE.
 
 ‐ For
homework
problems
requiring
calculation,
you
must
show
all
of
your
work,
 including
intermediate
steps,
in
order
to
receive
credit.


 ‐ Please
circle
final
answers
to
problems
that
require
computation;
doing
this
will
make
sure
 we
can
find
your
final
answer.

 ‐ For
questions
requiring
a
short
written
answer,
be
as
concise
as
possible
while
still
 explaining
your
answer.

 
 ‐ If
you
have
questions
about
concepts,
feel
free
to
post
questions
on
the
class
discussion
 board.
You
may
also
email
your
TAs,
but
do
so
only
after
you
have
looked
through
the
book
 for
an
answer
to
your
question.

 ‐ Homework
is
due
at
the
start
of
class
on
Tuesday
(by
11:15).
No
late
homework
will
be
 accepted.
 
 
 1) A
researcher
has
constructed
an
80%
confidence
interval
from
sample
data,
and
found
the
 interval
to
be
μ
=
45
±
8,
using
a
sample
of
n
=
25
scores.

 a. What
would
happen
to
the
width
of
the
interval
if
the
researcher
used
a
larger
sample
 size
(assuming
other
factors
are
held
constant)?
 b. What
would
happen
to
the
width
of
the
interval
if
the
researcher
constructed
a
90%
 confidence
interval
rather
than
an
80%
confidence
interval?

 c. What
would
happen
to
the
width
of
the
interval
if
the
sample
variance
increased
 (assuming
other
factors
are
held
constant)?
 d. What
would
happen
to
the
width
of
the
interval
if
the
mean
of
the
sample
were
twice
 as
large
(assuming
other
factors
are
held
constant)?
 
 
 2) A
researcher
obtains
a
sample
from
an
unknown
population
and
computes
a
sample
mean
of
 X = 43 ,
and
a
standard
deviation
of
s
=
6.

 a. If
the
sample
has
n
=
16
scores,
what
is
the
80%
confidence
interval
to
estimate
the
 unknown
population
mean.

 b. If
the
sample
has
n
=
36
scores,
what
is
the
80%
confidence
interval
to
estimate
the
 unknown
population
mean.

 c. If
the
sample
has
n
=
16
scores,
what
is
the
95%
confidence
interval
to
estimate
the
 unknown
population
mean.

 d. If
the
sample
has
n
=
36
scores,
what
is
the
95%
confidence
interval
to
estimate
the
 unknown
population
mean.

 
 
 3) Standardized
measures
seem
to
indicate
that
the
average
level
of
anxiety
has
increased
 gradually
over
the
past
50
years.
In
the
1950s,
the
average
score
on
the
Child
Manifest
 Anxiety
Scale
was
μ
=
15.1.
Suppose
a
sample
of
n
=
16
children
today
produces
a
mean
score
 of
 X = 23.3 ,
and
SS
=
240.

 a. Based
on
the
sample,
make
a
point
estimate
of
the
population
mean
anxiety
score
for
 children
today.

 b. Construct
a
90%
confidence
interval
estimating
the
population
mean
of
children
 today
 
 4) A
researcher
would
like
to
determine
how
physical
endurance
is
affected
by
a
common
 herbal
supplement.
The
researcher
measures
endurance
for
a
sample
of
n
=
9
participants.
 Each
individual
is
then
given
a
30‐day‐suppy
of
herbs
and,
1
month
later,
endurance
is
 measured
again.

For
this
sample,
endurance
increased
by
an
average
of
 X D = 6 
with
SSD
=
 216.
 a. Based
on
the
sample,
make
a
point
estimate
of
the
population
mean
difference
in
 endurance
for
individuals
taking
the
herbs.

 b. Construct
a
95%
confidence
interval
estimating
the
population
mean
difference
in
 endurance
for
individuals
taking
the
herbs
 c. Describe
what
this
confidence
interval
implies
about
whether
the
herbs
have
an
effect
 on
endurance
 
 
 5) A
developmental
psychologist
wants
to
determine
whether
infants
display
any
color
 preferences.
A
stimulus
consisting
of
four
color
patches
(red,
green,
blue
and
yellow)
is
 projected
onto
the
ceiling
above
a
crib.
Instants
are
placed
in
the
crib,
on
at
a
time,
and
the
 psychologist
records
how
much
time
each
infant
spends
looking
at
each
of
the
four
colors.
 The
color
that
receives
the
most
attention
during
a
100‐second
test
period
is
identified
as
 the
preferred
color
that
infant.
The
preferred
colors
for
a
sample
of
60
infants
are
shown
in
 the
following
table:
 
 Red
 Green
 Blue
 Yellow
 12
 
 a. b. c. d. What
are
the
null
and
alternative
hypotheses
for
this
experiment?
 What
is
the
critical
value
of
the
relevant
test‐statistic?
 What
are
the
expected
values
for
each
of
the
colors
in
this
experiment?
 Do
the
data
indicate
any
statistically
significant
preference
among
the
four
colors?
 Test
using
 α = 0.05 
and
explain
what
this
means
for
the
original
research
question.
 
 
 20
 10
 18
 6) A
local
county
is
considering
a
budget
proposal
that
would
allocate
extra
funding
toward
the
 renovation
of
city
parks.
A
survey
is
conducted
to
measure
public
opinion
concerning
the
 proposal.
A
total
of
150
individuals
responded
to
the
survey:
50
who
live
within
the
city
 limits,
and
100
who
live
in
the
surrounding
suburbs.
The
local
county
wants
to
determine
if
 there
is
any
difference
in
preference
for
people
who
live
in
the
city
and
people
who
live
in
 the
surrounding
suburbs.
The
frequencies
of
responses
are
as
follows:
 
 Opinion
 
 Favor
 Oppose
 City
 Suburb
 
 a. b. c. d. 35
People
 55
People
 15
People
 45
People
 What
are
the
null
and
alternative
hypotheses
for
this
study?
 What
is
the
critical
value
of
the
relevant
test‐statistic?
 What
are
the
expected
values?
 Do
the
data
indicate
a
statistically
significant
difference
in
the
preference
of
those
 people
living
in
the
city
and
those
people
living
in
the
suburbs?
Test
using
 α = 0.05 
 and
explain
what
this
means
for
the
original
research
question.

 
 
 
 ...
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This note was uploaded on 07/26/2010 for the course PSYC PSYC 60 taught by Professor ? during the Spring '09 term at UCSD.

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