What is a Clinical Trial Design & Mistakes You Should Avoid

Clinical Trial

Clinical trial design is all about the general technique, methodology and plan for conducting a study to inspect the safety and effectiveness of medical intervention. It can be like a vaccine, drug, solution, or medical equipment. Clinical trials are most of the time conducted in diverse types of phases, with each stage serving a particular kind of purpose.

You know what? The design of a clinical trial is critical to ensuring that the study generates lawful and dependable results. However, it is also crucial for you to know that designing a clinical trial can be demanding, and complex. Since that is the case, mistakes can take place and may compromise or harm the overall rationality, effectiveness, and dependability of the results of the study. In this post, you will learn about several common mistakes to avoid while designing a clinical trial.

Unsatisfactory sample size

We all know that the size of the sample has to be sufficient to accomplish the purposes of the study and ensure statistical power. Inadequate or wrong sample size can simply result in a type II error, in which the study fails to detect a significant difference between the intervention and control groups.

Lack of straightforward research question

You should mention the research questions appropriately and clearly. Also, ensure you align the study design with the research question. You must also ensure that you check that the research question is particular, measurable, achievable, relevant, and even time-bound. The point is simple, the questions are critical, and you must ensure that you pick them carefully.

Clinical Supplies 

Clinical trials require proper consideration of trial supplies to ensure the safety of the study. Operational challenges such as dosing, blinding requirements, expiration dates, temperature maintenance, and central depot locations can impact trial design and execution. By understanding such challenges, trial designers can mitigate possible errors and promise the smooth running of the trial. 

For example, designers can address the dosing challenges by using appropriate forms of medication and clear instructions. Exact temperature maintenance and central depot locations can promise trial supplies are delivered safely and on time. To consider these challenges is essential for practical clinical trials.

Bias in Clinical Trial Design 

Bias can enter the clinical trial design in numerous ways like:

– Selection bias 

It emerges when there is a systematic difference between the features of the participants in the treatment and control groups. For example, in case the treatment group includes only young adults and the control group comprises older adults only, the results can be biased towards the younger age group.

– Measurement bias

It happens when how data gets collected or measured is biased. For example, if a group of participants gets a more rigorous physical examination than the other group, the outcomes may be biased in the favour of the more methodically examined group.

– Observer bias

It takes place when the people gathering data or evaluating outcomes are biased in some way. As an example, if the fellows examining the outcomes are aware of which group is getting the treatment, they may accidentally report more positive outcomes for that group.

Deficient study duration

It is also true that the study duration has to be adequate to capture the outcome of interest. A short study duration may not offer sufficient time to detect changes in the outcome of interest. In contrast, a long study duration may result in participants dropping out or even being lost to follow-up. So, you have to pay proper attention to the duration of the study. 

Inappropriate or wrong study design

It is your responsibility to ensure that the study design is appropriate for the overall research question and the intervention being evaluated. For example, a randomized controlled trial may not be fair or effective for rare ailments. Similarly, an observational study may not be adequate assess the effectiveness of a new drug. So, there has to be proper design. With a correct format, everything would be effective.

Insufficient blinding

Blinding is masking the intervention from the participants, investigators, or even outcome assessors. Inadequate blinding can result in bias, as the participants or investigators may have proper expectations of the intervention’s effectiveness. So, whoever is organizing or performing the research or study, they have to ensure that there is appropriate blinding.

Inadequate control group

You should carefully select and adequately match the control group to the intervention/test group. It is to diminish the overall confounding factors. Insufficient control groups can lead to biased or spurious results. So, the persons who are conducting the research have to be mindful of this aspect.

Lack of randomization

Talking about randomization, it is a proper and effective procedure of assigning participants to either the intervention or control group in a random manner. Lack of randomization can end up in selection bias. In this, participants having the certain types of characteristics are more probable to be assigned to a single group than the other.

Insufficient statistical analysis

The statistical analysis should be appropriate for the research question and the data collected. You have to be mindful about this aspect as it matters. Inadequate type of statistical analysis can end up in unfair or bogus outcomes. Such results would be of no use for sure. So, you have to be sure that the performers perform sufficient statistical analysis and use the right tools while analysing the data.

Insufficient data collection

You have to ensure that the methods you use are apt for the clinical research question and the outcome of interest. An inadequate type of data collection can end up in missing or even incomplete data, which may compromise the overall cogency and even dependability of the results. So, you have to be double sure that there is a proper collection of data. After all, any research or study depends heavily on the data; if it is not up to the mark, other things can fall flat.

Short reporting

You should report the study in a transparent and accurate manner. It is to permit replication and verification of the results. Inadequate reporting can clearly result in incomplete or misleading data. So, there has to be proper reporting. After all, transparent reporting can ensure better outcomes and experience for sure, not to mention better acceptability from peers and regulatory agencies. 

Insufficient informed consent

A well-documented informed consent is the procedure of getting the voluntary agreement of the participant to take part in the study after offering proper information about the study’s purpose, procedures, and even possible risks and perks. There should never be a lack of consent for any of these studies, or it can be dangerous. Also, remember that just a consent is never adequate, the onus lies in ensuring comprehension of the information by the subject before the consent form is signed off. 


To sum up , it is true that clinical trials and researches are important. When you pay attention to the proper clinical research and ensure controlled clinical trial, you get the best possible results. Even the best researcher or studies can stand ineffective and unproductive if you don’t perform them effectively and properly.