A Quick Guide to Scientific Research Types
I've made a few videos, now, in which I teach you how to read a research paper. In the first video, I went over the different sections of a research paper---making sure to identify both the functions and level of importance in each one. In my most recent video, I talked about a few different types of research studies. However, while making the most recent video, I thought about how a video format is probably not the best when you're trying to teach yourself how to read research papers. I mean, who wants to watch an entire video in the middle of reading a research paper (spoiler: you teach yourself best by actually reading the papers) to get the answer to a question about how to read it. So, I wanted to make a little cheat sheet for you to reference in the midst of your studies.
For one, when it comes to scientific studies, there is a hierarchy of categories that take place before we get to the different study types. To start, scientific studies can fall into one of two broad categories: descriptive studies or analytic studies. Descriptive studies involve very hands-off research methods---these types of studies answer the observation-based questions like who, what, when, and where. The important part about these types of studies is that the scientists aren't really manipulating anything to get their results. They're simply watching what happens. In contrast, analytic studies answer the questions starting with "why" and "how". These studies oftentimes---thought not all the time---involve variables (called the independent variables) that are highly manipulated in order for researchers to come to a conclusion regarding the relationship between what they're manipulating and the outcome.
Under the umbrellas of descriptive and analytic studies lay more defining categories: survey studies (or cross-sectional studies), qualitative studies, experimental studies, and observational studies. Specifically, survey and qualitative studies fall under the descriptive studies category while the experimental and observational studies fall under the analytic studies category.
Starting with the survey studies/cross-sectional studies, these are the research papers where researchers observe a group of participants within a single population (ex.: the Congo, Gaza, the city of Denver, CO, etc.). These studies are often short term, capturing the conclusions from these populations in within a brief, pointed period of time. Then we have the qualitative studies, which involves absolutely zero numbers. Qualitative research consists of using non-numeric data, like human behavior or migration patterns of birds, to gain a deeper understanding about something. A great way to think about qualitative research is how documentarians uncover their stories: a lot of documentarians use primarily testimony, visual indicators, and pieces of footage to build a deeper understanding of the topic they're focusing on.
Moving to the analytic study sub-categories, we have the experimental studies. Experimental studies are very hands-on, as these involve experiments where researchers are controlling what participants are subject to an exposure of some sort or the invention for an exposure of some sort (like a bacteria vs an anti-biotic). These strictly-controlled experiments answer the more specific questions surrounding cause and effect, and they're considered the gold standard for things like clinical trials (aka the trials where prescriptions are tested before going to market). Finally, we have observational studies, which are passive studies where participants are simply observed in order to answer a "why", "how", or relationship question. For example, think of a study where a group of people were all prescribed a specific medication for a single diagnosis that they all share (hence, they were naturally going to take the medication whether researchers were observing or not) and the researchers are just weirdly watching like stalkers to see what happens overtime.
Now that we have the broader categories out of the way, now we can get into the specific research types. It is a good reminder, before we continue, that we are only covering a surface level of the different categories, as there are many sub-sections of research. So, here are the different types of research studies:
Study Type Name | Study Type Broad Category | Study Type Definition | When Should The Study Type Be Used? | Purpose of Study Type |
Randomized Controlled Trial | Experimental Study | Studies where researchers randomly allocate participants as treatment groups or control/placebo groups to find a conclusion regarding the relationship between two or more things. | When studying the impact of a medication, supplement, or other form of treatment or intervention. | To describe a relationship between a specific factor and specific treatment. |
Crossover Randomized Controlled Trial | Experimental Study | Studies where researchers allocate all participants the same treatment but each in a randomly chose order of treatment. | To more accurately test out the effect of the same medications on one person. | |
Cohort Study | Observational Study | Studies, oftentimes with data taken from databases, where researchers follow a specific group to gather data regarding the effects of a factor of interest. | When studying the likelihood of certain outcomes---like the health risks from long-term exposures, for example. | To determine whether certain exposures/ factors are associated with a specific health outcome. |
Case-Control Studies | Observational Study | Studies that compare groups of people with a specific condition/illness (cases) with similar groups of participants that don't have the condition (controls). In these studies, researchers look back in time to see what could've potentially led to the condition occurring. | When studying the potential causes of disease. | To determine association of diseases and what could have caused them to occur so more research can be done to validate the association. |
Qualitative Studies | Descriptive Study | Uses qualitative methods, like interviews and footage of behavior, to gain a deeper understanding about something. | When exploring broader concepts (behavioral, social, or economic concepts, etc.) to initiate more study into the phenomenon. | To start a path of understanding about qualitative factors (behavior, movement pattern, etc.) |
Once again, there are more than these types of research, but this is a great start. However, there is a broader category that I forgot to mention---namely because they're weird and don't usually involve experimentation or "in-the-field/lab" research. These types of papers are called secondary research studies, as they don't involve adding new information to the field, but instead compiling the already existing information to help scientists gather a general consensus on the state of different types of research. These types of publcations are important, as many studies exist in the world (both good and bad). Secondary research does a great job at helping filter out the not-so-great studies when coming up with an overall conclusion about a treatment, phenomenon, or concept.
Types of secondary research studies include:
Study Type Name | Study Type Definition |
Systematic Review | A structured summary of all available studies/primary sources surrounding a certain medical or scientific question. |
Meta-Analysis | A statistical technique that compiles all of the quantitative results from multiple different studies to find an overall conclusion or estimate. |
Narative Reviews (or Literature Reviews) | Short overviews that cover the existing knowledge on a concept. |
So, there you have it! I hope you can use this article to your advantage when teaching yourself to read research papers!
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