<s>
A	O
line	B-Application
chart	I-Application
or	O
line	O
graph	O
,	O
also	O
known	O
as	O
curve	O
chart	O
,	O
is	O
a	O
type	O
of	O
chart	O
which	O
displays	O
information	O
as	O
a	O
series	O
of	O
data	O
points	O
called	O
'	O
markers	O
 '	O
connected	O
by	O
straight	O
line	O
segments	O
.	O
</s>
<s>
It	O
is	O
similar	O
to	O
a	O
scatter	B-Application
plot	I-Application
except	O
that	O
the	O
measurement	O
points	O
are	O
ordered	O
(	O
typically	O
by	O
their	O
x-axis	O
value	O
)	O
and	O
joined	O
with	O
straight	O
line	O
segments	O
.	O
</s>
<s>
A	O
line	B-Application
chart	I-Application
is	O
often	O
used	O
to	O
visualize	O
a	O
trend	O
in	O
data	O
over	O
intervals	O
of	O
time	O
–	O
a	O
time	O
series	O
–	O
thus	O
the	O
line	O
is	O
often	O
drawn	O
chronologically	O
.	O
</s>
<s>
Some	O
of	O
the	O
earliest	O
known	O
line	B-Application
charts	I-Application
are	O
generally	O
credited	O
to	O
Francis	O
Hauksbee	O
,	O
Nicolaus	O
Samuel	O
Cruquius	O
,	O
Johann	O
Heinrich	O
Lambert	O
and	O
William	O
Playfair	O
.	O
</s>
<s>
For	O
example	O
,	O
if	O
one	O
collects	O
data	O
on	O
the	O
speed	O
of	O
an	O
object	O
at	O
certain	O
points	O
in	O
time	O
,	O
one	O
can	O
visualize	O
the	O
data	O
in	O
a	O
data	B-Application
table	I-Application
such	O
as	O
the	O
following	O
:	O
</s>
<s>
Understanding	O
the	O
process	O
described	O
by	O
the	O
data	O
in	O
the	O
table	O
is	O
aided	O
by	O
producing	O
a	O
graph	O
or	O
line	B-Application
chart	I-Application
of	O
speed	O
versus	O
time	O
.	O
</s>
<s>
Such	O
misunderstanding	O
of	O
the	O
mathematical	O
concept	O
of	O
something	O
called	O
A	O
being	O
a	O
function	O
of	O
something	O
called	O
B	O
as	O
expressing	O
a	O
causal	O
relationship	O
is	O
however	O
common	O
among	O
laypeople	O
(	O
and	O
reinforced	O
by	O
the	O
term	O
"	O
dependent	O
variable	O
"	O
)	O
and	O
is	O
not	O
dependent	O
on	O
representation	O
in	O
a	O
line	B-Application
chart	I-Application
.	O
</s>
<s>
Charts	O
often	O
include	O
an	O
overlaid	O
mathematical	O
function	O
depicting	O
the	O
best-fit	B-Algorithm
trend	O
of	O
the	O
scattered	O
data	O
.	O
</s>
<s>
This	O
layer	O
is	O
referred	O
to	O
as	O
a	O
best-fit	B-Algorithm
layer	O
and	O
the	O
graph	O
containing	O
this	O
layer	O
is	O
often	O
referred	O
to	O
as	O
a	O
line	O
graph	O
.	O
</s>
<s>
It	O
is	O
simple	O
to	O
construct	O
a	O
"	O
best-fit	B-Algorithm
"	O
layer	O
consisting	O
of	O
a	O
set	O
of	O
line	O
segments	O
connecting	O
adjacent	O
data	O
points	O
;	O
however	O
,	O
such	O
a	O
"	O
best-fit	B-Algorithm
"	O
is	O
usually	O
not	O
an	O
ideal	O
representation	O
of	O
the	O
trend	O
of	O
the	O
underlying	O
scatter	O
data	O
for	O
the	O
following	O
reasons	O
:	O
</s>
<s>
It	O
is	O
highly	O
improbable	O
that	O
the	O
discontinuities	O
in	O
the	O
slope	O
of	O
the	O
best-fit	B-Algorithm
would	O
correspond	O
exactly	O
with	O
the	O
positions	O
of	O
the	O
measurement	O
values	O
.	O
</s>
<s>
In	O
either	O
case	O
,	O
the	O
best-fit	B-Algorithm
layer	O
can	O
reveal	O
trends	O
in	O
the	O
data	O
.	O
</s>
<s>
Further	O
,	O
measurements	O
such	O
as	O
the	O
gradient	O
or	O
the	O
area	O
under	O
the	O
curve	O
can	O
be	O
made	O
visually	O
,	O
leading	O
to	O
more	O
conclusions	O
or	O
results	O
from	O
the	O
data	B-Application
table	I-Application
.	O
</s>
<s>
A	O
true	O
best-fit	B-Algorithm
layer	O
should	O
depict	O
a	O
continuous	O
mathematical	O
function	O
whose	O
parameters	O
are	O
determined	O
by	O
using	O
a	O
suitable	O
error-minimization	O
scheme	O
,	O
which	O
appropriately	O
weights	O
the	O
error	O
in	O
the	O
data	O
values	O
.	O
</s>
<s>
Such	O
curve	B-Algorithm
fitting	I-Algorithm
functionality	O
is	O
often	O
found	O
in	O
graphing	B-Application
software	I-Application
or	O
spreadsheets	B-Application
.	O
</s>
<s>
Best-fit	B-Algorithm
curves	O
may	O
vary	O
from	O
simple	O
linear	O
equations	O
to	O
more	O
complex	O
quadratic	O
,	O
polynomial	O
,	O
exponential	O
,	O
and	O
periodic	O
curves	O
.	O
</s>
