Difference Between Cohort and Panel Study

Key Difference – Cohort vs Panel Study

When speaking of research, cohort and panel study are two research designs used by researchers between which a key difference can be identified. Based on the research problem, and the objective of the researcher, the suitable design for the research is being chosen. First let us comprehend the basic difference between the two studies. A cohort study is a longitudinal study conducted on a group of people who share a common characteristic. A panel study is also a longitudinal study, but the key difference between the two is that unlike in a cohort study, the same participants are used throughout, in a panel study.  This article attempts to highlight the differences between cohort and panel study in detail.

What is a Cohort Study?

First let us pay attention to the cohort study. A cohort is a group of people that share similar characteristics. For example, children born in 2008 belong to a single cohort since they share a common characteristic. This can even be an experience that a group of individuals underwent. For example a group of individuals who became refugees due to conflicts in a country.

A cohort study refers to a longitudinal study that falls into the category of observational studies. In a cohort study, the researcher observes a group of people for a long period of time. Since the research goes on for a long period of time in most situations, it is vital that the researcher keeps in touch with the members of the cohort. The success of the research largely depends on this ability of the researcher. Cohort studies are conducted both in the natural sciences as well as in  the social sciences.

Let us take an example where a cohort study can be used in the natural sciences. If a researcher wants to identify potential risk factors for a particular disease, to find out at what stages the disease emerges, under what conditions, etc. he can conduct a cohort study in a particular region. However, at the inception, the cohort will include people who have not yet being diagnosed with the disease, who share a similar characteristic such as women born in a particular year. As the researcher conducts the study over time, he will notice the development of the disease in some members of the cohort, this will allow him to identify the potential risk factors, etc.

Difference Between a Cohort and a Panel Study

What is a Panel Study?

A panel study is also a longitudinal study. The key difference between a cohort study and a panel study is that unlike in the case of a cohort study, in a panel study the same individuals are used in throughout the study. This allows the researcher to examine the exact changes that have taken place over time.

However, conducting panel studies can be difficult when participants either refuse to contribute to the research on later occasions or when some of the participants cannot be found. This usually affects the results of the research clearly and leads to a bias. Another key issue that researchers face is reactivity. This takes place when the same questions are posed from individuals again and again. This once again creates a bias in the opinions of the participants.

Key Difference - Cohort vs Panel Study

What is the Difference Between a Cohort and a Panel Study?

Definitions of Cohort and Panel Study:

Cohort Study: A cohort study is a longitudinal study conducted on a group of people who share a common characteristic.

Panel Study: A panel study is also a longitudinal study where the same participants are used throughout the study.

Characteristics of Cohort and a Panel Study:

Type of study:

Cohort Study: Cohort study is a longitudinal study.

Panel Study: Panel study is also a longitudinal study.


Cohort Study: Individuals who share a common characteristic of experience are chosen for the sample. This is known as a cohort.

Panel Study: The same individuals are used as the sample throughout the study.


Image Courtesy:
1. Wikiguides Cohort 1 by study day By Philippe (WMF) (Own work) [CC BY-SA 3.0 or GFDL], via Wikimedia Commons
2. “HarmCausedByDrugsTable” by User:Tesseract2 – “Scoring drugs”, The Economist, data from “Drug harms in the UK: a multi-criteria decision analysis”, by David Nutt, Leslie King and Lawrence Phillips, on behalf of the Independent Scientific Committee on Drugs. The Lancet. 2010 Nov 6;376(9752):1558-65. doi:10.1016/S0140-6736(10)61462-6 PMID:21036393. [CC BY-SA 3.0] via Commons