An
increase
in
demand
means
a
shift
of
the
demand
curve
.
A
decrease
in
demand
means
a
shift
of
the
demand
curve
.
There
are
five
principal
factors
that
the
demand
curve
for
a
good
or
service
:
changes
in
the
prices
of
related
goods
or
services
,
changes
in
income
,
changes
in
tastes
,
changes
in
expectations
,
and
changes
in
the
number
of
consumers
.
are
usually
goods
that
in
some
way
serve
a
similar
function
.
When
the
price
of
a
substitute
rises
,
the
demand
for
the
original
good
.
When
the
price
of
a
substitute
falls
,
the
demand
for
the
original
good
.
are
usually
consumed
together
.
When
the
price
of
a
complement
falls
,
the
demand
for
the
original
good
.
When
the
price
of
a
complement
rises
,
the
demand
for
the
original
good
.
Goods
for
which
demand
increases
when
income
rises
are
known
as
goods
.
When
income
rises
,
the
demand
for
a
normal
good
.
When
income
falls
,
the
demand
for
a
normal
good
.
Goods
for
which
demand
decreases
when
income
rises
are
known
as
goods
.
When
income
falls
,
the
demand
for
an
inferior
good
.
When
income
rises
,
the
demand
for
an
inferior
good
.
Economists
usually
lump
together
changes
in
demand
due
to
fads
,
beliefs
,
cultural
shifts
,
and
so
on
under
the
heading
of
changes
in
,
or
.
When
tastes
change
in
favor
of
a
good
,
the
demand
for
the
good
.
When
tastes
change
against
a
good
,
the
demand
for
the
good
.
The
current
demand
for
a
good
is
often
affected
by
about
its
future
price
.
When
the
price
is
expected
to
rise
in
the
future
,
the
demand
for
the
good
today
.
When
the
price
is
expected
to
fall
in
the
future
,
the
demand
for
the
good
today
.
The
demand
curve
shows
the
combined
quantity
demanded
by
all
consumers
.
When
the
number
of
consumers
rises
,
the
demand
for
the
good
.
When
the
number
of
consumers
falls
,
the
market
demand
for
the
good
.