When starting any market research project, one of the first things you need to ask yourself is whether or not your sample size is achievable. After all, a research study can only be truly valuable if it is both reliable and representative of your audience. Selecting the ideal sample size can be tricky and should be based on solid statistics whilst at the same time being realistic for the size of the target market. That’s why it’s important to do your sample size research as early in your proposal stage as possible, to ensure you don’t have any problems with delivery further down the line. When it comes to healthcare market research, you need to be even more specific. What criteria do your patients need to meet? Is there a particular type of healthcare specialist you need to interview and are there any factors that could be holding you back from recruiting this particular professional? The key to selecting the perfect sample size is to review all the data accordingly so that, where possible, you can be confident that you have based your sample on actual statistics and research rather than rough estimates. Read on to find out more…
1) How many physicians are there in the UK?
If recruiting healthcare professionals, one of the most important things to consider is the number of physicians available in the UK that treat the specific condition you are researching. The Digital NHS Catalogue is a great place to start and provides up-to-date data on NHS staff numbers across a range of specialities, which can help you to identify exactly how many treaters there are throughout the UK for your specific condition and therefore how realistic your sample size is. It’s also a useful tool if you are conducting patient market research, as it can help you to figure out how many finders you will be able to reach out to in order to help you recruit your patients.
If you have access and if hard stats are not publicly available, you could organise a telephone conversation with key opinion leaders or consultants in your target area to get a view of things such as the number of physicians treating the disease, or an idea of how well used a new drug may be in their region. This can help to get a better view of how realistic your suggested sample size is. If you have accesstop line to a panel of physicians, a quick poll can also be a useful exercise prior to going into field. Even though this takes time upfront, it’s well worth the effort to avoid any major delays during the project.
2) Are there any specific hospitals or centres to recruit from?
Whatever specialist area you are looking into, researching the hospitals or treatment centres you can recruit from is a very important step, especially if you are planning to conduct one-on-one methodologies such as face-to-face interviews as you can get a better understanding of whether or not your sample size in your chosen area is realistic and if there are any travel logistics you need to consider. Are there any centres that specialise in this specific area? Or any hospitals that have bigger treatment facilities? If so, where are they located?.
If you want to speak with respondents who are based at specialist centres, then you might want to consider interviewing multiple respondents per hospital. This type of restriction can have a knock-on-effect when it comes to your final sample selection as well as your chosen methodology later down the line.
3) What desk research is available?
It’s also worth looking at the different types of secondary research available to back up your findings. For example, if your research will be looking at a specific drug type, is it approved by NICE? When was it approved, and if not, why not? Are there any exceptions as to why a healthcare professional would or wouldn’t prescribe the drug? It’s important to consider these factors as the answers will most likely impact on the number of HCPs and patients available for you to recruit.
Another important statistic to look at is the incidence rate of the condition– if you’re looking at a rarer disease such as haemophilia, we would recommend comparing the incidence statistics to that of a more common condition such as asthma or diabetes to help put your findings into perspective. This will help you work out how easy or hard patient recruitment may be in a given area, but will also help you work out how many healthcare professionals might be treating a rarer disease where there may be little published numbers available.
4) What experience do you have in this area?
Another key step to consider is to look at your own previous experience in the area. Look at some of your past sample sizes for previous medical fieldwork projects: were the sample sizes achieved? If not, why not? If you are using a recruitment agency or recruiter, ask them to provide feedback on their previous experiences: by reviewing earlier results and identifying any previous problems, you can make informed decisions about your chosen approach to ensure you don’t repeat any previous mistakes. Likewise, if a certain approach has proved successful in the past, it might be worth considering incorporating it into your current medical fieldwork methodology this time around, too.
5) What websites can I use to support my decision?
There are a number of external websites that can help you to gather the information you need to make intelligent decisions regarding your sample size and chosen methodology. Obviously, the most suitable websites will depend on the area you have decided to study, but as a general rule of thumb the NHS, NICE and MIMs websites are a great place to start.
Here are some other documents that you might find useful when deciding on your sample size:
Our therapy area guides also include the latest information on incidence rates, diagnosis and treatment of various conditions that can be used to help with feasibility assessments – sign up here to receive the latest guides as and when the series is updated.