Research Writing

Ex post facto research Characteristics Advantages Examples

Ex post facto research consists of an explanatory investigation, with the aim of pointing out factors that contribute to certain phenomena occurring. The literal translation of this term means “from the past fact”. 

That is, the researcher uses it to work his way back, observing events that followed a certain event and their relationship with this first fact. 

In the scientific universe, there are different types of research , which differ in relation to the nature of the method, the end and the means. In this last item of differentiation, we find: experimental research, participant research, action research , survey , case study and, the little known Ex post facto. 

In this article, we will present the meaning of this type of investigation, the advantages of applying it and some examples of researches that were carried out in this way. Check out!

What is Ex post facto research?

The meaning in literal translation, “from the past fact”. As the name implies, this is a type of investigation that aims to verify whether there is a relationship between a phenomenon that occurred after a certain fact and the fact itself. 

Its object of study is a variable that cannot be changed, from observation of data to make a comparison with another variable.

In this way, this type of research aims to analyze the cause and effect relationships between a given event and its possible consequences. In other words, the goal boils down to seeking answers to cause and effect relationships and thus understanding a little better what has already happened.


The main characteristic is that, in this case, data are gathered after the occurrence of the event. In addition to this, other particularities of this research model are:

  • Variables are immutable; 
  • It consists of a correlational study (cause and effect relationships are established from the researcher’s observation); 
  • It seeks to find the reason why a certain phenomenon occurs.
  • It is a descriptive study, as the researcher describes the facts that happened.


The great advantage of carrying out an Ex post facto research lies in the fact that, through it and from a careful analysis of variables, events and their consequences, it is possible to understand and find answers to certain occurrences. 

In the social field and in the area of ​​health sciences, this type of investigation is the most used and aims to propose solutions for the consequences arising from a certain phenomenon. 

Ex post facto versus case study research

While the Ex post facto study focuses on conducting an investigation from past facts, the case study seeks to examine its object of study in depth and more openness. Therefore, the main difference is that in the Ex post facto the variables are not manipulable, while in the case study this can already happen when studying the phenomena. 

Another distinguishing aspect is related to the nature of the research: Ex post facto is quantitative (based on numbers and statistics), while the case study is qualitative (texts, interviews and interpretation). 

Ex post facto research versus experimental research

Both experimental and Ex post facto research analyze cause and effect relationships, however, only experimental research is open to manipulating the variables of a given phenomenon. 

To better understand the differences between ex post facto and experimental research, consider the examples below:

  • Experimental research: a type of treatment was applied to a group of students and the dropout rate was later observed.
  • Ex post facto research: a questionnaire is applied to a group of students who dropped out of school, with the aim of investigating the reasons that led to school dropout. 

Examples of applying Ex post facto research

It can be used in several areas of knowledge. Examples of the application include: 

1. Post-pandemic dropout

Data on school dropout at primary and secondary levels during and after the Covid-19 pandemic are evaluated.

During the investigation, the reasons why children and young people left their studies in this period are observed and an attempt is made to find a common denominator. 

2. Carrying of weapons

In this case, the research seeks the relationship between the authorization to carry firearms and the increase in violence.

For this, it is also necessary to define which cities will be used for analysis.

3. Transmission of women’s football games

The research investigates the data regarding the interest in women’s soccer, specifically after the start of broadcasting of the games on open television channels. 

4. Digital books

With the rise in prices of physical books and the rise of technologies that make pleasure possible through screens, a student decides to investigate the increase in the consumption of digital books through free downloads or at a reduced price, and the influence of new formats on reading habits. Brazilian reading

5. Consumption of ultra-processed products

Inflation has a strong impact on the prices of foods rich in nutrients and suitable for a balanced diet.

For this reason, a researcher decided to study how this has influenced the diet of the Brazilian population, which opts for cheaper solutions that, however, do not offer nutritional quality.

How to do an Ex post facto research?

1 – Define a problem

All scientific research starts from a problem and the Ex post facto method is no different. Then look at your object of study and identify a difficulty that needs to be resolved.

Suddenly, a gap related to the chosen topic can also give rise to problematization. 

Every research problem is presented in the form of a guiding question , that is, a relevant question capable of moving the entire investigation.  

2 – Build hypotheses

You found that your research problem fits the Ex post facto methodology, after all, the facts that will be studied have already happened. Then, it is time to create hypotheses , that is, possible solutions to the identified problem. 

3 – Define the sample

The research, the group needs to have experienced the situation that contextualizes the problem.

4 – Collect data

There are many ways to collect data, and the most used technique in Ex post facto studies is the application of a questionnaire with open and closed questions.

5 – Observe the variables

With the collected data in hand, observe the dependent and independent variables. The first group includes the factors you measured with the survey. The second encompasses magnitudes capable of dividing the studied sample into subgroups.

Thus, it is easier to tabulate the research data, that is, the separation of information by categories and subcategories.

Remember that when variables cannot be quantified, they are considered qualitative.

6 – List the situations

The time has come to analyze and interpret the data, relating the elements measured by the study. In this way, it is worth linking situations and even making comparisons with other groups of participants.

The cause-effect relationship cannot be ignored, after all, this is the investigation objective of an Ex post facto research. Therefore, evaluate what were the things that happened after the studied event.

7 – Use other procedures in your investigation

The Ex post facto study can coexist with other methodological procedures, such as documentary research and life history . Therefore, combine different methodologies so that your study becomes even more complete and profound.

Related Articles

Leave a Reply

Your email address will not be published. Required fields are marked *


Back to top button