Recruitment of research participants

In this post we will look at the recruitment of participants to your research study including approaching them and your research materials.

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An essential part of any research study that involves human participants is recruiting individuals to take part. These may be members of the general public or those with specific attributes that you’re interested in, such as being members of a particular organization, within a particular age group or those with specific medical conditions.

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Approaching participants

No matter who your participants are you need to think about how to advertise your study so you gain sufficient interest whilst also ensuring that you’re not intrusive or aggressive in your approach.

Your approach should be inviting but you must ensure that potential participants don’t feel pressured or obligated to take part. Some common methods for approaching potential participants include the use of:

  • Posters
  • Telephone or Video calls
  • Letters
  • Social media posts

It is important to be aware some methods can be more intrusive than others. It’s always best, if possible, to approach potential participants indirectly rather than directly.

Using posters, flyers, leaflets or social media adverts are all excellent ways to gain interest without people feeling pressured into taking part. Other good methods include using emails or letters addressed to either large groups (distribution lists) or publicly available contact details. A fuller list of methods organised by how intrusive they are can be found here.

Using Gatekeepers

Gatekeepers might be another option that could help facilitate your recruitment strategy. Gatekeepers, as the terms suggests, act as a channel for conveying information for a large group of potential participants and sometimes you may need to seek their permission before you’re able to access a specific group.

For example:

This might be a professional organization where you’d like to speak with the employees. It’s likely that you’ll need permission from a manager or even CEO before you could approach these individuals.

Gatekeepers are not only able to provide access to an otherwise difficult to reach group, but they can also help with your recruitment strategy by circulating details of the study to the group on your behalf.

There are of course other potential methods for recruitment that involve contacting people directly through telephone calls, video call, instant messaging, chat groups or even in person. However, many times these are considered to be ‘cold calling’ techniques as the potential participant is often caught off guard by the invitation and may not feel as though they can decline. For this reason, it is advisable to choose a less intrusive method of approaching participants so they have both time and space to consider your invitation and decide if they wish to take part.

A word of caution if using gatekeepers

One must be aware of the possible power dynamic that may exist in organisations and make efforts to mitigate this and ensure that possible participants are free to choose if they would like to take part.

For example, if the gatekeeper is a manager who agrees to circulate the information to those they directly line manage, the employees may feel obligated to take part to either be viewed in a more favourable light or out of fear for possible repercussions for not taking part.

To help mitigate this, it is recommended that the person who circulates the information is impartial and that the message which is circulated re-iterates that participants are free to make their own decision, without any possible negative repercussions should they decline.

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Recruitment materials

When approaching your potential participants, you should use recruitment materials (also known as advertisements) to explain the purpose of your study as well as what’s involved and any specific requirements.

Recruitment materials may include items such as posters, flyers, leaflets, social media text, letters, emails or videos. They should strike a balance between capturing someone’s attention, and ensuring they are not overly coercive or promise unrealistic benefits. Materials should also be short and to the point, you will have an opportunity to provide more detailed information at a later date.

The essential elements of a good advertisement include:

What the study is about:

Describe in general terms what your study is investigating, such as: ‘ The study is about the correlation between blue light emissions from hand held devices (e.g. mobile phones) and a lack of quality sleep.’

What will participants be asked to do:

Specify any tasks that the participants will be asked to do during the study, such as: ‘You will be asked to take part in a one time, 1 hour long Zoom interview about your views on mobile phone usage and the quality of your sleep. You will also be asked to complete a diary for 7 days prior to the interview about mobile phone usage and your sleep patterns.’

What are the inclusion or exclusion criteria:

Clarify any specific attributes the participants must have or activities they must do in order to take part, such as: ‘You must use a mobile phone daily.’

How can participants contact the researcher:

Provide contact details such as an email address or telephone number so those interested in taking part can contact you. You may also choose to use a QR code that can be read by one’s smartphone that takes them to your website or automatically populates an email. For example, ‘You can contact the researcher by email:; or by phoning 0161–777–7777’.

Monetary amounts are not permitted:

You may clarify that one will be compensated for their time or entered into a prize draw but you must not include details of how much as this is deemed to be coercive. For example ‘You will be compensated £20 for your time’ is deemed to be potentially coercive. Instead this should be written as ‘you will be compensated for your time’ and the specific amount included in other study documentation.

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Knowledge check

Let’s take a look at what you have learned. Read the case study below and choose an option from the multiple choice question below it. You may choose more than one option.

Case study example:

‘You’re conducting a research study about the impact of the COVID pandemic on the parents or guardians of school aged children.

As your child also attends school, you’re part of a WhatsApp group with all the other parents or guardians from your child’s class. Some of the parents or guardians you know and others you’ve never met before. As you already have their numbers, you’d like to send the advertisement to the group to see if anyone would be interested in taking part.

Part of this message would ask that if anyone is interested that they send an email to your generic research email address as opposed to replying in the group chat.

You would also make it clear that they are under no obligation to reply to the group text.’

“Would this be an acceptable recruitment strategy for your study?” An accessible version of the above quiz question is available with the possible answers here.

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In this post we explored how you might approach and recruit participants to your study.

Once potential participants respond to your advertisement and express an interest in taking part, you need to provide them with more specific information about what the study involves. This is done through the use of a participant information sheet.

Take a look at our post about Participant Information Sheets next or go back to the full list of posts in this series.

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