<s>
Cross-sectional	B-General_Concept
data	I-General_Concept
,	O
or	O
a	O
cross	O
section	O
of	O
a	O
study	O
population	O
,	O
in	O
statistics	O
and	O
econometrics	O
,	O
is	O
a	O
type	O
of	O
data	B-General_Concept
collected	O
by	O
observing	O
many	O
subjects	O
(	O
such	O
as	O
individuals	O
,	O
firms	O
,	O
countries	O
,	O
or	O
regions	O
)	O
at	O
the	O
one	O
point	O
or	O
period	O
of	O
time	O
.	O
</s>
<s>
Analysis	O
of	O
cross-sectional	B-General_Concept
data	I-General_Concept
usually	O
consists	O
of	O
comparing	O
the	O
differences	O
among	O
selected	O
subjects	O
.	O
</s>
<s>
This	O
cross-sectional	B-General_Concept
sample	O
provides	O
us	O
with	O
a	O
snapshot	O
of	O
that	O
population	O
,	O
at	O
that	O
one	O
point	O
in	O
time	O
.	O
</s>
<s>
Note	O
that	O
we	O
do	O
not	O
know	O
based	O
on	O
one	O
cross-sectional	B-General_Concept
sample	O
if	O
obesity	O
is	O
increasing	O
or	O
decreasing	O
;	O
we	O
can	O
only	O
describe	O
the	O
current	O
proportion	O
.	O
</s>
<s>
Cross-sectional	B-General_Concept
data	I-General_Concept
differs	O
from	O
time	O
series	O
data	B-General_Concept
,	O
in	O
which	O
the	O
same	O
small-scale	O
or	O
aggregate	O
entity	O
is	O
observed	O
at	O
various	O
points	O
in	O
time	O
.	O
</s>
<s>
Another	O
type	O
of	O
data	B-General_Concept
,	O
panel	O
data	B-General_Concept
(	O
or	O
longitudinal	O
data	B-General_Concept
)	O
,	O
combines	O
both	O
cross-sectional	B-General_Concept
and	O
time	O
series	O
data	B-General_Concept
ideas	O
and	O
looks	O
at	O
how	O
the	O
subjects	O
(	O
firms	O
,	O
individuals	O
,	O
etc	O
.	O
)	O
</s>
<s>
Panel	O
data	B-General_Concept
differs	O
from	O
pooled	O
cross-sectional	B-General_Concept
data	I-General_Concept
across	O
time	O
,	O
because	O
it	O
deals	O
with	O
the	O
observations	O
on	O
the	O
same	O
subjects	O
in	O
different	O
times	O
whereas	O
the	O
latter	O
observes	O
different	O
subjects	O
in	O
different	O
time	O
periods	O
.	O
</s>
<s>
Panel	O
analysis	O
uses	O
panel	O
data	B-General_Concept
to	O
examine	O
changes	O
in	O
variables	O
over	O
time	O
and	O
its	O
differences	O
in	O
variables	O
between	O
selected	O
subjects	O
.	O
</s>
<s>
Cross-sectional	B-General_Concept
data	I-General_Concept
can	O
be	O
used	O
in	O
cross-sectional	B-General_Concept
regression	O
,	O
which	O
is	O
regression	O
analysis	O
of	O
cross-sectional	B-General_Concept
data	I-General_Concept
.	O
</s>
