14 Advantages and Disadvantages of a Randomized Controlled Trial

A randomized controlled trial is a study where people get allocated by chance alone to receive one of several unique clinical interventions. One of them is the standard of comparison, which is traditionally referred to as the control group. The control can be from the use of a standard practice, offering a placebo, or to use no interventions whatsoever. Then the results from this group get compared to the other treatments to determine if positive results occur.

The individuals who take part in a randomized controlled trial are called subjects or participants. Researchers use this method to compare outcomes after every participant receives a specific intervention. That’s why this method is a quantitative study. It uses controlled experiments where investigators can study two or more interventions in a series of people who receive them in a randomized order.

When we look at the randomized controlled trial advantages and disadvantages, it is clear to see that this tool is a simple approach for researchers to use. It is also popular because it can provide a powerful database of results.

List of the Advantages of Randomized Controlled Trials

1. Randomization prevents the deliberate manipulation of results.
A randomized controlled trial works to prevent skewing or the deliberate manipulation of results by researchers or participants. Because each subject gets assigned to a specific group randomly, the removal of choice works to get rid of selection bias. This advantage prevents scientists from subconsciously or deliberately assigning patients to specific groups receiving active treatment if it seems like they would be likely to benefit from it. That would make the outcome seem to be more beneficial than it really would be.

The opposite could also occur. Researchers who want to demonstrate the potential danger of a specific treatment could assign participants who have a higher risk of complications to the active group.

2. It provides immediate comparative results that researchers can use.
Randomized controlled trial processes use one treatment option that gets directly compared to another one as part of the project. This method makes it much easier to establish which one has a superior outcome. That means the study design can make causal inferences so that we have access to the strongest empirical evidence of efficacy or an inability to perform as intended.

Although the placebo effect can sometimes minimize the outcomes of this advantage, researchers can know immediately if something seems to work or know for sure that a new idea needs to get pursued.

3. This method minimized the confounding factors.
The act of randomization in a controlled trial setting minimizes confounding because of the unequal distribution of prognostic factors. It makes groups become comparable through the collected data according to known and unknown factors that investigators find during the research process.

Even a blocked randomization effort can make groups comparable when they fall within known confounding factors.

4. It offers a higher level of statistical probability.
When a study is significantly randomized, then the statistical test of significance is readily interpretable for investigators. That means the results generated from these efforts have a greater level of reliability when compared to other research methods. The sample size from a randomized controlled trial avoids type one and type two errors when it is adequately powered.

That means it can stop issues where the null hypothesis is either incorrectly rejected or accepted.

5. Investigators can use multiple methods of randomization.
Randomized controlled trials can get designed through the use of several different structures. Depending on the results that researchers hope to achieve, this method can use a stratified approach, random clusters, or crossover clusters. Some situations might call for complete randomization of the participants into investigatory groups. There’s also the step-wedge and block methods that work well in specific areas of study.

6. It allows researchers to have control of the exposure event.
Even though the population groups in a randomized controlled trial get masked, researchers still get the advantage of having control over the exposure. That means investigators can work with the amount of a treatment option, the timing of its application, and the duration of the study. That means several different groups can get studied at once to determine if changes in frequency can provide more results than a standard dose alone or nothing at all.

That’s why a properly designed study is well-regarded as being a true measure of efficacy. It provides researchers with high levels of internal validity.

List of the Disadvantages of Randomized Controlled Trials

1. The logistics of a randomized controlled trial can be demanding.
Researchers and participants may need to endure a long trial run to ensure that there is enough data for comparison. This disadvantage can result in the loss of relevance for an idea because a practice can move away from the idea being studied by the time the trial is at a place where publication is possible. Because validity requires multiple sites and groups for scientists to manage, the power calculation might demand a vast sample size that goes outside of the resources of the investigators.

If a research project cannot manage the logistics of a randomized controlled trial, then the data these efforts produce will be questionable at best.

2. Some randomization efforts may be predictable.
Some randomized controlled trials use block methods to select participants for a research project. When this option is the primary selection option for investigators at the start of an effort, then the allocation of subjects can become predictable. That means this disadvantage can result in a higher level of selection bias in the data when the study groups are eventually unmasked on the way toward publication.

If this disadvantage occurs within the context of a randomized controlled trial, then it provides a limited amount of external validity. This issue can continue to grow when artificial environments get introduced in the research setting.

3. There can be some applicability issues with randomized controlled trials.
Trials that test for efficacy may not be widely applicable when using the randomized control method. When an effort to test for effectiveness is large, then it becomes more expensive, and that issue can also impact the results achieved. The results from this work might not always mimic real-life treatment situations, such as inclusion and exclusion criteria, so what happens in the context of the investigation may not provide relevant data. Highly controlled settings are not always the best solution to use where there’s a need to find specific results.

4. This research method comes with some ethical limitations.
The active randomization requires a certain level of clinical equipoise. Investigators cannot ethically provide random groups of patients their treatment options unless both selections have an equal level of support within the clinical community. That’s why the issue of informed consent is a significant disadvantage when using this approach for a clinical trial. Researchers must use generalities instead of specificity when talking to patients about what their participation will look like in the coming days.

When subjects hear generalities, then they are more likely to assume that they are receiving the designated treatment. That’s why the placebo effect can be so disruptive to randomized controlled trials. If someone feels like their items are working as intended, then it can create an internal psychological effect that creates a similar result.

5. Some research cannot be ethically performed using this model.
The traditional argument against the use of randomized controlled trials involves the effects of a parachute on the survival rate of skydivers. You cannot place some individuals in a position where their life is immediately threatened by the structure of the research that investigators want to pursue. That means there are certain limitations with this approach that can limit the amount of usable data we can collect.

Because of this disadvantage, there is limited scope to the research that benefits from a randomized controlled trial. Most of the efforts involve preventive or therapeutic treatments.

6. The data does not show you the critical information needed for results.
When researchers use a randomized controlled trial, then the outcome shows that the treatment option being studied has potential or it does not. The results will not give professionals the critical information that is needed to benefit human life. You will not know what patients are going to experience the most advantages when they receive the intended product.

Randomized controlled trials must be very large to achieve statistical significance because of this disadvantage. It is the only way to account for heterogeneity within the participant groups. That means the final data that investigators receive tends to have centralized tendencies, so it is not going to be representative of the final population group at the individualized level.

7. Participants who participate in this research aren’t always reflective of their demographic.
Randomized controlled trials don’t take into account the history of each participant. The subjects who tend to seek out treatments in this manner are often those who have tried everything else and are desperate for a positive outcome. That makes it challenging for investigators to generalize the results so that they can apply to everyone because the population tends to be people who always enroll in the studies instead of being people who never do.

8. It is an expensive proposition.
Even if the randomized controlled trial only uses one baseline group and a single treatment demographic, the length of the research requires a significant investment. It is one of the most expensive methods of collecting data in terms of time and money. You’re looking for relative risk within a population group and odds ratios that can determine specific outcomes. If the investigators inadvertently study two population groups, then the information may not be useful.

An example of this issue is a 2015 study on this use of a hamstring exercise with male amateur soccer players. Over the course of 12 months, the randomized controlled trial from van Der Horst, et. al showed that there was a statistically significant reduction in the incidence of hamstring injuries for players proactively using the exercise. The average age was 24.5, but the deviation rate was almost four years. Someone at 20 can react differently than another individual at the age of 28.


Randomized controlled trials are considered the gold standard for current research methods. The findings from this work have a higher level of statistical reliability because of the comparative processes that investigators follow. Although there can be logistical issues that impact the results in adverse ways, the outcomes are generally accepted as a useful finding.

There are ethical limitations and applicability issues that must come under consideration for anyone thinking about the design of a trial such as this. Informed consent is often impossible because the placebo used to create comparative results can mimic the desired outcome. That’s why subjects often get told that they might receive the treatment or the placebo. If someone is in the control group without treatment, even the fact that they’re in a research study can produce positive results.

That’s why we must approach the advantages and disadvantages of a randomized controlled trial with caution. It may be the best option for publication, but this pursuit might not be the best investigative choice in every situation.

Blog Post Author Credentials
Louise Gaille is the author of this post. She received her B.A. in Economics from the University of Washington. In addition to being a seasoned writer, Louise has almost a decade of experience in Banking and Finance. If you have any suggestions on how to make this post better, then go here to contact our team.