Methods and techniques of investigation

A method is a series of procedures with a specific purpose. A technique is the way we carry out those procedures.

Thus, research methods are the strategies for the scientific search for knowledge, while research techniques are the tools used to carry out this search.

The best way to understand the difference between method and technique is presented by Münch and Ángeles in the phrase: “If the method is the path, the technique provides the tools to travel that path.”

In any investigation, the best way to solve the problem of interest must be considered through the different research methods. And depending on the method chosen, the appropriate techniques will be applied.

What are the research methods?

A research method is the strategy that the researcher uses to conduct the search for new knowledge. The Philosophy Dictionary presents the meaning of “method” as “an orderly, repeatable and self-correcting research procedure, which guarantees the obtaining of valid results.”

The word “method” derives from the Greek meta which means “beyond” and hodos which means “way”. The method means the most suitable way to achieve an end.

There are different research methods depending on the purpose of the research and the context in which it is carried out. This is established from the problem and the objectives that are intended to be met to solve the problem.

Here are the most commonly used research methods.

experimental method

The experimental method is a quantitative research method that is applied when the factors to be discovered can be managed. This method is based on numerical data and measurements, which is why it is considered ideal in the natural sciences, such as chemistry and biology.

The researcher seeks to discover the effect of something on a system. For example, you want to know how fish oil affects the plasma membrane of liver cells. The experiments that have to be done to test different concentrations of fish oil are designed, whether it will be tested in cultured liver cells or in laboratory animals, what and how the plasma membrane will be measured, among other things.

The experimental method is also used when you want to try a different technique to synthesize a chemical compound. For example, the synthesis of a drug using procedures that are more environmentally friendly and with better efficiency.

Randomized controlled trial

The randomized controlled trial is the research method used to compare the effects of a treatment on a group. In this type of method, you work with two or more groups of individuals, where one of the groups is the control group and the other is the treated group. The control group will not receive treatment, so it is expected that its characteristics will not change during the investigation and will serve as a reference for comparison.

The characteristics of the participating groups should be as close as possible, in order to rule out that the results obtained are due to the treatment and not to another factor. Participating groups should be roughly the same age range, the same weight range, and the same male to female sex ratio.

In many of the randomized controlled methods, the participants do not know if they are receiving the treatment, which is why it is known as a blinded study. This is done to lessen subjective psychological effects on objective measurements.

For example, you want to know how a compound X changes the blood pressure of humans. For this, a sample of people with similar characteristics and who are willing to participate in the study is chosen. The researchers distribute the participants into a control group and a group that will receive compound X. After a stipulated time, blood pressure will be measured in both groups and the corresponding statistical analyzes are made.

Ethnographic method

The ethnographic method investigates the way of life of a group of people. It is the preferred method in anthropology, because it allows us to understand the activities of human beings in a specific time and place.

In this method, the researcher settles in the community and interacts with its inhabitants, hearing, seeing and participating in common activities. He then analyzes his observations and explains the topics of interest that arose.

For example, if you want to discover the reasons for the migration of young people from a country, one of the ways to approach this research would be through the ethnographic method.


Meta-analysis is a quantitative method that takes data from several previous quantitative investigations and re-analyzes it. This method makes it possible to take advantage of the data obtained by other researchers without having to repeat the sampling or recruitment of individuals, increasing the number of participants.

For example, a group of researchers led by Peter Joshi did a meta-analysis to determine the genetic basis for a long and healthy life. For this they analyzed the results of more than 600 thousand genetic data generated by 24 studies in different parts of the world, finding new information.


Meta-synthesis is a qualitative method that evaluates previous studies on the same topic and re-analyzes them. This method is applied in the social sciences, with the advantage of covering a larger number of participants without the need to repeat interviews or surveys.

For example, in an investigation on depression and anxiety, meta-synthesis was used, collecting studies related to these conditions published from January 2002 to May 2012. These researchers discovered that patients assume depression and anxiety as the same , which may affect your evaluation and treatment.

Study of cases

Case studies are the method of investigation when you are in the presence of unusual events or conditions. This type of approach seeks to describe the event in great detail, so that it serves to alert about its handling if it occurs again.

For example, Golfard and Grasso presented the study of two cases of cystinuria, a rare genetic disease characterized by kidney stones, where they describe and analyze the traits and peculiarities that these two patients experienced.

Systematic review

Systematic review is a research method that examines in detail the conclusions of studies conducted on a topic. It requires few resources, although it can take a long time to perform the search and analysis in an objective and reproducible way.

For the systematic review, a question is formulated, and based on this, a literature search protocol is designed. It is important to use different bibliographic databases, such as PUBMED, Web of Science or EMBASE.

References should be chosen following rules that ensure that studies are not duplicated and that they are relevant to the research.

For example, three researchers from a public health center in Northern Ireland conducted a systematic review on how to treat isolated older adults. They evaluated three databases, finding more than 500 studies, of which they selected 33. Of these they concluded that there are different ways to remove older adults from isolation and that they may or may not work depending on the person.

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What are the investigation techniques?

The technique is the set of instruments and means through which the method is carried out. Abbagnano’s dictionary of philosophy defines technique as a set of rules capable of effectively directing any activity.

Investigative techniques can be applied at different stages of the investigation. You can have techniques to collect samples or participants, to classify the information, measure the parameters of interest and other needs raised depending on the research method chosen. Here are some of the most commonly used research techniques.

Bibliographic search

The bibliographic search is a valid documentary research technique for any type of research. It consists of investigating the sources of information related to the problem to be developed. These sources can be of various types, such as books, magazines, theses, newspaper or scientific articles, among others.

The bibliographic search is the fundamental technique in meta-analysis, meta-synthesis and systematic review. In addition, it is the basis of all research, since from this the researchers can conduct the study with better precision.

The use of extensive databases of bibliographic material facilitates the search, which, based on keywords and certain criteria, provides the collection of information sources with great speed and with minimal effort.

The digitization of content and the Internet are valuable tools in the application of this technique.


Scheduling is a research technique that allows the orderly collection of information on the sources consulted. This consists of registering the references that we are going to use as part of our research on cards or index cards (on paper or digital). This not only saves us time by having the information we need at hand, but also money, since we do not need to buy the material consulted.

There are different types of tokens depending on their function. We have reference cards where the data of a publication is placed, such as author, title, name of the book, publisher and year of publication. The worksheets are also used where we write down the phrase or paragraph of interest and where we obtained it from, to be able to cite it correctly in our research work.


The survey consists of obtaining information about a part of the population through the use of the questionnaire. This can be done in person or through digital means and can be both qualitative and quantitative. For example, when a questionnaire has a scale where “Never” is 0 and “Always” is 5, the responses of the participants can be quantified.

The survey is widely applied in the study of product marketing and in the social sciences, such as psychology.

For example, in a study to explore health professionals’ level of happiness and how they treat patients, 400 hospital employees were given four different surveys. In these surveys happiness, self-compassion, conscience and stress were evaluated on different scales.


The interview is a research technique where the researcher requests information from a person for a specific purpose. Widely applicable in the social sciences, it addresses personal aspects of the research participants.

For example, in one study, three mothers with children with disabilities were given a semi-structured interview, that is, an interview where there are prepared questions but others may arise as it develops. These questions were related to the expectations, afflictions and feelings of the women towards the physical problems of their children.

You may also be interested in seeing Types of interview .


Observation is a research technique that consists of perceiving something with a specific intention and objective. It can be implemented in both social and natural sciences, and must be framed in the specific research area.

Observation can use auxiliary instruments, such as telescopes, microscopes, cameras, among others.

For example, a group of astronomers observed the evolution of a supernova for two years using an instrument called a spectrograph. A supernova is a star that explodes releasing matter and energy. These astronomers discovered that cosmic dust is produced after the explosion, which could be the seed for the creation of galaxies.


The experiment is the research technique of excellence in the natural sciences. This consists of choosing a system where some conditions can be modified and then studying the effect. A system can be a plant in a pot, a cell in a test tube, or an iron rod.

In an experiment, it is ideal to keep as many fixed conditions as possible and only vary one factor, so that any observed change can be attributed to that factor.

For example, we have four types of yeast and we want to know which one is the best for making bread. We prepare a mixture of flour, water and salt and separate it into four equal parts. To each part we add a type of yeast (in the same quantity), we knead it and we bake the same time. In the end, we evaluate the characteristics of each bread, and the best will be due to the yeast used.

Animal models

Animal models consist of laboratory animals that are kept under controlled conditions and with which experiments are performed. The advantage of using animals as models lies in the ease of handling, rapid reproduction and housing. Animals are also used to alter their genetic code and thus discover the function of a gene.

Among the animal species most used as models we have mice, rats, guinea pigs, rabbits, dogs, pigs and baboons. Animals are used to determine the toxic concentrations of drugs and the effects of certain treatments before they are applied to people.

Computer simulations

Computer simulations consist of the virtual representation of data. It has the advantage of dispensing with reagents and work material, as well as serving to predict possible effects without the need for experiments.

For example, a group of scientists simulated by computer the extinction of the Neanderthals man, through the migration patterns of modern man from Africa to Asia and Europe.

Cell cultures

Cell cultures are a cell growth and maintenance technique for study. Normal cells, such as cells from the liver and arteries, or tumor cells, can be cultured. Genes in cells can also be modified, making it easier to discover their function.

Cell cultures are used to discover the effect of compounds on cell metabolism. Also to reproduce viruses, which alone cannot do it.

For example, using a certain cell type, you can infect a certain virus and then test the ability of compound X to multiply them.

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