Solved – Difference between longitudinal data and panel data

panel dataterminologytime series

When trying to grasp the terminology behind some time-series concepts, I have came across Rob Hyndman's article which states the following

Econometricians use “panel data” while statisticians use “longitudinal
data” to refer to collections of time series.

After searching (check the search done bellow), I end up with the idea that the concepts are the same.

Is the fields that the terms are being used the only difference between longitudinal data and panel data?

Search

  1. Longitudinal data:

1.1. This blog entry defines it as

Longitudinal data typically arise from collecting a few observations
over time from many sources, such as a few blood pressure measurements
from many people.

1.2. This article defines it as

Then longitudinal analysis is the study of collections of variables;
in most applications the variables are strongly associated. We can
associate each time point with a separate variable, in the spirit of
the original definition of the term variable.

  1. Panel:

2.1. This article it looks like Panel Analysis is the same as Longitudinal Analysis

Longitudinal or panel data analysis refers to the statistical analysis
of pooled data which consists of a cross‐section of units (e.g.,
countries, firms, households, individuals) for which there exist
repeated observations over time.

2.2. This Wikipedia page goes within the same line as the article in 2.1.

In statistics and econometrics, panel data and longitudinal data
are both multi-dimensional data involving measurements over time.

2.3. This Quora answer use the terms interchangeably

longitudinal or panel data, observations of multiple phenomena over
multiple time periods for the same data units; involves repeated
observations of the same variables (e.g., people) over periods of
time; can prove cause and effect, but time-consuming and expensive

Best Answer

Longitudinal and panel data are synonym. There are only three possibility:

  1. cross section: several variable one time only
  2. time series: one variable only measured many times
  3. panel/longitudinal: several variables measured several times

Moreover note that, at least in econometrics, the fact that we have a panel dataset do not imply that we must use models for panel data. For example a simple VAR (vector autoregression) is a typical time series model and do not represent a panel data technique, even if the dataset would be suitable for.

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