IA Tips…How to explain your PARTICIPANTS

Travis DixonInternal Assessment (IB)

This post explains what characteristics of your participants you should explain for the IB Psych IA.

You must “explain” the five elements of the exploration: Design, Sampling technique, Controls, Materials, Participants to get full marks for the IA exploration (4 marks). In this post we’ll look at how to explain your choice of participants. 

Explaining participant choices is quite difficult. I would aim to have one really excellent explanation that clearly shows how you are controlling for an extraneous variable with your participant choice. The other one or two characteristics could be based on practical reasons. Here’s how to do this…

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Describing Participants

The first step is you need to describe your participants. What characteristics are relevant to include in your description? Studies typically include the following:

  • Sample size
  • Age (range and mean)
  • Gender (% male & female)
  • Occupation (e.g. students, )
  • Language (first language spoken)
  • Ethnicity or Race (% of major ethnicities/groups)

In your IA report you should describe your participants based on the above characteristics. Here’s an example taken from my example IA in the IA Teacher Support Pack:

Participants: Our participants were 20 female high school students in an international school in Japan (16-19 years, mean age = 17.2). Participants were IB students and fluent in English, either as a first or second language, mostly Japanese ethnicity with some others.” 

This is an effective description because it concisely summarizes the characteristics in just two sentences. Now the reader knows who my participants were, I can explain why I chose to study this particular group.

If you’re not sure what to explain in your exploration, re-read the original article of the study you’re replicating. You can take some tips from what they’ve done.

Explaining Participants

For your materials, controls and participants, I recommend explaining at least two or even three choices. For example, explain three materials, three controls and two or three characteristics of participants. The three most logical participant characteristics for you to explain are:

  • Language 
  • Age 
  • Gender 

Language: Every experiment requires some kind of comprehension of the instructions. You therefore need participants who can speak and understand the language of your experiment so they can give their informed consent and know what to do. This is a very basic explanation. If your experiment involves a high level of reading comprehension or it’s testing memory of information, you probably decided to choose participants with a minimum level of English (or other language) fluency. Otherwise, differences in literacy levels could be a confounding variable. This is another good thing to explain.

Age: A basic reason for choosing a particular age (e.g. above 16 years old) is to avoid the necessary requirement of having parental consent for younger participants. This could be a standard explanation to include. I recommend giving another reason as well. Think about other benefits to having an older (or younger) sample. You might have also chosen your participants because of the age range. It might’ve been beneficial to have a narrow age range (e.g. all students, or all teachers). This might also be relevant to explain.

Gender: Students often get confused when they try to consider gender as another variable in their study. Remember that we are not allowed to compare gender differences in our IA because this is not a true experiment. Therefore, you should aim for a sample with a fairly balanced mix of gender. Having said that, if you think that there might be a reason to suspect that boys and girls will have vastly different scores, you could limit your sample to one gender and explain why. You can see I did this in my (fictional) IA example quoted above.

Other Options? Sometimes you might choose a specific class, like the IB Spanish SL class or something similar. Such a detail is very relevant to describe and explain in your report.


Below is the full paragraph from the example IA in the IA TSP. You can see that I explained four characteristics, but to avoid writing things twice, I wrote a note to see explanations of age and gender in my controls section.

My explanation of gender was as follows:

“Gender: We also studied only female participants because this is what they did in the original because research suggests media exposure affects men and women differently.”

While describing 5 characteristics sounds like a lot, you can see how it can be done concisely in just two sentences. Then you can follow with your explanations. Don’t make the mistake of thinking that explanations don’t have descriptions. Even the IB’s command term definitions show this as a describe is “a detailed account or summary” and an explanation is “a detailed account or summary,  with reasons or causes.” My best advice is to follow the State-Describe-Explain (What-H0w-Why) method.

The exploration section will be quite long. It took me about 600-800 words to explain all five aspects in enough detail to ensure my exemplar would score top marks. Attention to detail is the key!

Got a question about the IA? Post it in our Facebook group (For Students or For Teachers).