The hidden cost of choosing the wrong study design

Before statistics. Before ethics approval. Before data collection.

Comes design.

I learnt this the long way around.

And yet, study design is one of the most underestimated stages of research.

Many postgraduate students feel an understandable pull to “get started”. To begin collecting data. To feel productive. To move forward. Design can feel abstract, theoretical, even slightly intimidating. So it gets less time than it deserves.

But the truth is that design determines everything.

It determines the types of conclusions you can draw. It determines the risk of bias. It determines how easily your work can be published. And perhaps most importantly, it determines how smooth or how frustrating your research journey will be.

When the study design and research question are aligned, research feels purposeful. When they are misaligned, everything feels heavier than it should.

In this blog post, I want to explore how to choose the right study design and why matching your research question to your study design is not just a methodological decision, but a productivity and wellbeing strategy. I will also share a story from early in my own career that taught me this lesson the hard way.

Study Designs and Research Methods Resource Hub

Why researchers underestimate study design

If I am honest, I understand why study design gets neglected. When you start a research degree, or even a new project, there is an energy to it. You have an idea. You have momentum. You want to do something. Collect something. Analyse something. Produce something.

Design, by comparison, can feel slow and slightly abstract. You sit with questions. You read. You sketch possibilities. You realise there are more options than you thought. Observational. Experimental. Qualitative. Mixed methods. It can feel like standing in the baking aisle of a supermarket with too many choices and not enough certainty.

So what do many people do?

They default to what they have seen before. They copy the design of a published paper. They choose the most impressive-sounding option. Or they quickly pick one that sounds right to be able to complete the proposal and hope the design will somehow clarify itself along the way.

The problem is that design is not decoration. It is not something you add on later. It is the backbone of the entire project.

If your backbone is slightly misaligned, everything downstream compensates because what you are doing does not feel aligned with your research question and objectives. And then you start to doubt yourself. Not a fun place to be.

You have the ability and you know it. But the problem is misalignment. And misalignment costs time, and confidence.

My 2012 systematic review lesson

Let me take you back to 2012. We were away on a writing retreat, laptops open, papers spread out, productivity amplified. It felt productive and purposeful, the kind of focused academic space you imagine will make everything fall neatly into place.

I was working on my first systematic review. We had even organised a writing retreat. I remember feeling quite proud of that. We were being serious academics. Focused. Intentional. Productive.

The review was exploring etiology and risk. At the time, however, I tried to structure it using the methodology of an effectiveness systematic review. That was the framework I was most familiar with. It was what I had seen published. So I assumed that was simply how systematic reviews were done.

There was very little accessible guidance available to me then. I relied heavily on published papers and tried to reverse-engineer what they had done. On the surface, that seems sensible. In reality, it meant I was trying to fit a square peg into a round hole.

And I struggled.

Before the manuscript ever reached my co-authors, I had spent a great deal of time reshaping that square peg. Filing down the corners. Adjusting the language. Reworking sections so that it would “fit” the effectiveness structure. By the time it reached them, it had round enough corners to be acceptable.

But it took far longer than it needed to.

What I did not realise at the time was that I was working with the wrong underlying blueprint. Years later, when I learnt more about the different types of systematic reviews, it suddenly made sense. I had not been doing an effectiveness review at all. I had been doing an etiology and risk review.

The question required a different methodological lens.

If I had paused at the very beginning and asked, “What type of review is this really?” I would have saved myself a significant amount of time, cognitive overload, and unnecessary self-doubt. The issue was never my ability. It was that I had not spent enough time getting the question and the design properly aligned before trying to execute it.

The cost of poor alignment

When we talk about choosing the wrong study design, it can sound like a purely technical issue. A methodological adjustment. A minor academic inconvenience.

In reality, the cost is far more personal.

First, there is lost time. Time spent rewriting sections that never felt quite right. Time spent trying to force methods to answer questions they were not designed to answer. Time spent fixing problems that could have been prevented with a few extra hours of deep thinking at the start. And time, especially during a Masters or PhD, competes with work, family life, rest, and everything else that makes you human. This is where many capable researchers start working longer hours unnecessarily, trying to compensate for a structural problem with personal effort.

Second, there is cognitive overload. When your design and question are misaligned, every decision feels heavier. Inclusion criteria become confusing. Analysis choices feel uncertain. Your brain works harder than it needs to.

Third, and perhaps most importantly, there is self-doubt. When things feel harder than expected, many researchers assume the problem is them. “Maybe I am not cut out for this.” “Maybe I am missing something obvious.” Often, you are not missing ability. You are missing alignment.

And this is where productivity and wellbeing intersect.

Intentional study design, in addition to being scientifically rigorous, is about protecting your energy. It is about reducing avoidable friction. It is about creating conditions where your ambition can be channelled constructively.

The research question shapes the design

One of the most important principles in research is deceptively simple: the research question determines the study design. If you are unsure how to choose a study design, this is your anchor principle. Not the other way around.

Yet I regularly see students start with, “I want to do a randomised controlled trial” or “I think I will do a cohort study,” before they have fully articulated what they are actually trying to find out. 

A more helpful starting point is to ask: what kind of question am I asking? Broadly speaking, research questions tend to fall into a few categories:

• Do I want to describe something? For example, prevalence or characteristics of a population.
• Do I want to assess associations or explore potential risk factors?
• Do I want to predict an outcome?
• Do I want to test an intervention?

Each of these objectives naturally aligns with different study designs.

If you want to measure prevalence, a cross-sectional design may be appropriate. If you want to explore risk factors, a cohort or case-control study might make more sense. If you want to test an intervention, then an experimental design becomes relevant.

When you are unclear about which of these you are really trying to do, you end up in methodological no-man’s-land. You borrow elements from different designs. You stretch definitions. You persuade yourself it will be fine.

It rarely is.

I often use a simple analogy with my students. Research is a bit like baking. You do not start by choosing a recipe at random. You first decide what you feel like baking. A cake? Bread? Something savoury? Only once you are clear on the outcome do you choose the recipe that will get you there.

Your research question is what you feel like baking. Your study design is the recipe.

If you start with the wrong recipe, it does not matter how carefully you follow the steps. You will not get the outcome you intended.

Matching your study design to the size of your degree

There is another layer to this conversation that is often overlooked, especially in postgraduate research. The “right” study design is not only determined by your question. It is also shaped by the scope of your degree.

If you are completing a Masters where 50 percent of the programme is devoted to research, the size of your project will be smaller than someone doing a 100% research Masters. A Masters student wants to run a large randomised controlled trial with multiple follow-up points and complex statistical modelling. It sounds impressive and it reads well in a proposal. But in practice, it can become overwhelming, underpowered, and unnecessarily stressful.

A well-designed cross-sectional study that answers a clear question robustly is far more valuable than an underpowered trial that cannot realistically deliver on its promise.

Part of intentional study design is asking these two questions:

• What is the most appropriate design for my research question?
• What is realistic within the boundaries of my degree?

Choosing a design that fits the above means you are designing a project that can be completed well, within the time and resources available, without compromising your wellbeing in the process.

A simple decision-making framework for how to choose a study design

If you are feeling slightly overwhelmed at this point, let me simplify it. You do not need to memorise every possible study design. Here is the step-by-step framework I now teach my students and use in my own work when guiding them through research proposal development and study design selection:

Step 1: Clarify what you are really trying to know

Write your research question in one sentence. Then ask yourself: am I trying to describe, assess associations, predict, or test an intervention? If you cannot answer that clearly, pause here. Do not move on.

Step 2: Refine and reshape the question

Allow yourself to shape and reshape your question before committing to a methodology. Run this by your supervisor or a fellow student. Sleep on it. It is okay to decide on a research question and then to revisit it later on, so even if you have a few different research questions to play around with at this stage, it is fine. You may need to go back to this step as you progress through the next steps.

Step 3: Identify the broad design category

Once your objective is clear, identify the family of designs that naturally aligns with it. Observational? Experimental? Qualitative? Mixed methods?

Knowing this will help you search in the right cupboard for the most appropriate study design. Read up on the different study designs in the family before you move to the next step. Looking at the Design Tree on this page will be helpful here. You’ll also find an overview of the most commonly used study designs in the Study Designs & Research Methods Resource Hub.

Step 4: Pressure-test feasibility

Ask yourself:

• Do I have access to the required sample size?
• Do I have the time to complete this within my degree?
• Do I have the skills, or support, to analyse the data appropriately?
• Is this design proportionate to the scope of my qualification?

If the honest answer is no, adjust early. It is far easier to recalibrate now than six months into data collection.

Step 5: Check reporting standards

Once you have tentatively selected a design, look up the relevant reporting guideline. If you are planning an intervention, explore CONSORT. For observational studies, STROBE. For systematic reviews, PRISMA. You’ll find all of them and more on the Equator Network website. If your proposal cannot logically align with a recognised reporting framework, that is often a useful warning sign.

A quick self-check before you finalise your design

Before submitting your proposal, ask yourself:

• Is my research question clearly articulated in one sentence?
• Can I clearly state whether I am describing, associating, predicting, or testing?
• Does my chosen study design logically follow from that objective?
• Is this design feasible within the time and resource constraints of my degree?
• Am I choosing this design because it fits my question, or because it sounds impressive?
• Being clear on the above will save you months of frustration.

A practical starting point if you feel stuck

If you are reading this and thinking, “This all makes sense, but I still do not know where to begin,” you are not alone. One of the reasons I struggled back in 2012 was that I did not have a clear, structured starting point. I had papers. I had examples. I had enthusiasm. What I did not have was a simple overview of the different study designs and how they connect to different types of research questions.

That gap is exactly why, in collaboration with the Wits Cricket Research Hub, I developed the Study Designs & Research Methods Resource. It is particularly helpful if you are at proposal stage, refining your question, or supervising students who are navigating these decisions for the first time.  

It is designed to help you:

• Understand the main families of study designs
• See how different research questions map onto different approaches
• Avoid common mismatches between question and methodology
• Choose a design that is both appropriate and feasible

Think of it as the “design cupboard” neatly organised. Instead of guessing which recipe might work, you can step back, look at the options calmly, and make a deliberate choice.

I now encourage my postgraduate students to spend dedicated time working through this resource before they finalise their proposal. Not after they have collected data. Not once they feel stuck. At the very beginning. Because the goal is not simply to complete a research project. The goal is to complete a research project well, without unnecessary stress, wasted time, or erosion of confidence.

If you are at the proposal stage, or even just shaping an idea, this is your moment to slow down slightly so that you can move forward with clarity. It might feel like you are delaying progress. In reality, you are protecting it.

Ambition, calmly

There is something I say often to the researchers I work with: pursue ambition, calmly. You are allowed to care deeply about your work. You are allowed to want it to be rigorous, publishable, impactful. Ambition in research is not something to apologise for. But ambition without clarity can quickly become anxiety.

When you rush into a study design that does not truly fit your question, or your degree, you are not being ambitious. You are being reactive. And reactivity tends to create unnecessary stress. Calm ambition, on the other hand, is deliberate.

It pauses at the beginning. It asks better questions. It tolerates a little uncertainty while shaping the research question properly. It chooses a design that fits, rather than one that impresses. Choosing the right study design is one of the most practical ways to practise ambition, calmly.

It is not glamorous work. No one applauds you for spending two extra weeks refining your research question. But your future self will. And when your methods flow logically, your analysis feels coherent, and your writing becomes clearer, you will experience something that is surprisingly rare in postgraduate research: research that feels aligned.

Frequently asked questions about choosing and matching a study design

How do I match my research question to the right study design?

Start by clearly articulating your research question in one sentence. Then identify whether you are trying to describe, assess associations, predict, or test an intervention. Once that is clear, select the study design that naturally aligns with that objective. Matching your research question to your study design should feel logical.

How do I choose the right study design for my research question?

Start with your objective, not the method. Ask yourself whether you are trying to describe a population, assess associations, predict an outcome, or test an intervention. Once that is clear, identify the family of study designs that naturally aligns with that purpose. Then pressure-test feasibility within the scope of your degree. Clarity of question first. Design second.

What is the most common mistake postgraduate students make when selecting a study design?

In my experience, it is choosing a design because it sounds impressive rather than because it fits the question. Randomised controlled trials are powerful, but they are not always appropriate or feasible, especially at Masters level. A well-designed observational study that answers a clear question robustly is far stronger than an underpowered trial that creates unnecessary stress.

Can I change my study design after starting my proposal?

Yes, particularly in the early stages. Refining your research question and adjusting your design before data collection is part of good research practice. It is far better to recalibrate during proposal development than to realise six months later that your design does not truly answer your question.

How detailed does my research question need to be before I select a design?

It needs to be clear enough that you can state, in one sentence, what you are trying to find out and which category of question it falls into. If you cannot confidently say whether you are describing, associating, predicting, or testing, spend more time refining the question before committing to a methodology.

Where can I learn more about different study designs and research methods?

If you would like a structured overview that connects research questions to appropriate study designs, the Study Designs & Research Methods Resource Hub provides a practical starting point. It walks you through the main design families and helps you make an intentional, proportionate choice for your project.

Key take-home lessons on choosing the right study design

If you remember nothing else from this post, remember this:

• Your research question determines your study design. Always start with the question.
• Misalignment between question and design costs time, energy, and confidence.
• Not every project needs to be large or complex to be rigorous and valuable.
• Feasibility is not a compromise. It is a strength.
• Spending more time at the beginning often means spending less time fixing problems later.

If you are at the beginning of a project, take enough time to shape the question. Explore the different study designs. Use structured resources. Ask for feedback. Then move forward with clarity. That is how we pursue ambition, calmly.

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Professor Benita Olivier is a healthcare research leader and the founder of Research Masterminds, a platform helping researchers balance productivity and wellbeing. With over 100 publications and 35 supervised postgraduates, she bridges academia and personal development to help researchers thrive.

Looking for some extra support on your PhD research journey?
Check out the Research Masterminds Success Academy — an online hub where you can develop skills, stay motivated, and still have time to enjoy life beyond your research!
👉 https://www.researchmasterminds.com/join-the-academy

Thank you for the cover photo by Pixabay.

This blog post was created through a collaborative process. I provided the initial ideas, draft content and related research, and AI (ChatGPT) assisted in restructuring and refining the material. Final edits and insights are entirely my own.

Views expressed are my own and do not reflect those of my employers.