There are four main types of data: time series data which records values over time, cross-sectional data which records values at a single point in time, pooled data which combines time series and cross-sectional data, and panel data which is a type of pooled data that tracks the same observational units over time. Panel data allows analysis of both differences between observational units as well as changes within units over time, making it a combination of cross-sectional and time series data. It is often used to study things like changes in households or businesses using a unique identifier to follow each unit longitudinally.

1. By
Kamran Khan & yumna

2.  Data:
Originally collected observation (from
which conclusion may be drawn) are
collectively called data

3. Types of Data
There are four types of data:
1. Time series
2. Cross-section
3. pooled (i.e., combination of time series
and cross-section) data.
4. Panel a special type of pooled data in
which the same cross-sectional unit is
surveyed over time.

4. A time series is a set of observations on the
values that a variable takes at different
times. It is collected at regular time
intervals, such as daily, weekly, monthly
quarterly, annually, that is, every 5 years
(e.g., the census of population),

5. 2)Cross-Section Data.
Cross-section data are data on one or more
variables collected at the same point in time,
such as the census of population conducted
by the Census Bureau every 10 years.

6. 3) Pooled Data.
In pooled, or combined, data are elements of
both time series and cross-section data.
4) Panel, Longitudinal, or Micro panel Data.
This is a special type of pooled data in which
the same cross-sectional unit (say, a family
or a firm) is surveyed over time.

7.  If we have a cross section data collected from the
"same sample" with "an identification code" such that
we can follow changes of a given respondent over time,
it is called a data panel. It carries characteristics of
both cross section and time series.
 An example would help. Suppose we have collected
dropout data from a set of same schools (say from 100
schools) for 5 years time with unique school
identification code for all the years, we call it a school
(panel).
 we can use this data to compare dropout pattern
between schools (cross section). we can also analyses
the changes of dropout pattern over time for individual
schools or for the entire sample (Time series).
 There are separate econometric techniques to deal with
panel data, Fixed effect models and random effect
models are popular.

8.  if your degree of measurement is one day,
then your life for today is cross-sectional
data . your life for past ten days is time series
data. And life of many persons including you
your family over past ten days is panel data.