IB Psychology IA Criteria: Your Checklist to Scoring Top Marks
Everything you need to know to get a strong score on your IB Psychology IA.
Clear breakdowns of every criterion, up-to-date for 2025, and built to help you understand how it’s marked.
What Is the IB Psychology IA?
The Psychology IA is a short research project where you carry out a simple experiment based on a well-known study, and show that you understand how psychological research works: designing a method, collecting data, and analyzing results.
You’ll replicate an existing study with a small change, test it on a group of participants, and write up your findings in a formal report.
Word count: 1,800–2,200 words
Weighting: 25% of your final grade at SL, 20% at HL
Assessment: Marked externally against four fixed criteria (A–D)
Done well, the IA can lift your final IB Psychology grade.
Ready to take your Psychology IA to the next level? Join a one-on-one trial session where an IB examiner will walk you through your research design, analysis, and evaluation - helping you strengthen your argument and boost your final mark.
IB Psychology IA Criteria Overview
Your Psychology IA is marked against four criteria (A-D), worth 22 marks in total. Each one focuses on a different skill - from planning your experiment to evaluating your results.
Criterion A: Introduction (6 marks) - Explains what you’re investigating and why. Includes your aim, background theory, and clear hypothesis.
Criterion B: Exploration (4 marks) - Covers how you designed and carried out your study: method, sampling, procedure, and ethics.
Criterion C: Analysis (6 marks) - Focuses on how well you process and interpret your data using descriptive and inferential statistics.
Criterion D: Evaluation (6 marks) - Assesses how you discuss your findings, strengths, limitations, and possible improvements.
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IB Psychology IA Criterion A: Introduction (6 Marks)
What does a strong introduction accomplish?
Your introduction sets the tone for the whole IA. It shows the examiner that you understand the theory behind your study, your variables make sense, and that you can think like a researcher.
What examiners look for
A clear aim that states exactly what your experiment is testing.
A short, relevant background theory or model that explains why this question matters.
Independent and dependent variables that are both defined and measurable.
A research and null hypothesis that logically follow from the theory.
Examiners reward introductions that feel purposeful - every line should move from broad context to a specific, testable question.
Common pitfalls
Writing a page of theory without linking it to your actual study.
Using vague variables (“stress,” “attention”) without saying how they’re measured.
Leaving key terms undefined or mixing up cause and effect.
Presenting multiple hypotheses or skipping the null.
How to reach the top band in Criterion A (6/6)
Keep it concise - aim for about half a page of focused writing.
Define every variable and show how it connects to the background theory.
Use transitions that make your logic obvious: theory → aim → variables → hypothesis.
End with a clear sense of direction so the reader knows exactly what the experiment will test.
A strong introduction makes the examiner’s job easy - it frames the study so clearly that every section after it feels coherent.
IB Psychology IA Criterion B: Exploration (4 Marks)
What does an effective exploration look like?
Criterion B is about how you carried out your investigation. Examiners want to see that your method is clear, controlled, and ethical - and that it directly supports your aim and hypothesis.
What examiners look for
A logical research design (e.g., independent or repeated measures) that fits your question.
A clear sampling method with enough detail to show who your participants were and how they were chosen.
Identification of key controlled variables and how you kept them consistent.
A short list of materials used and why they were appropriate.
A step-by-step procedure that could be replicated from your description.
Reference to relevant ethical guidelines (consent, right to withdraw, confidentiality, debrief).
A strong Exploration reads like a clear set of instructions - someone else could repeat your study and expect similar results.
Common pitfalls
Describing what you did but not why it fits your research question.
Forgetting to mention controls or counterbalancing.
Using vague participant descriptions (“a few classmates”) instead of specifics.
Ignoring ethics or leaving them to the end as an afterthought.
How to reach the top band in Criterion B (4/4)
Keep the section concise - about one page of well-organized detail.
Justify your key choices briefly (“A repeated-measures design was used to reduce participant variability”).
Write in past tense and keep the focus on clarity, not storytelling.
Make sure your design, procedure, and ethics all align with your aim and variables.
A well-written Exploration shows control and intention - the examiner should finish this section confident that your study was sound, practical, and ethical.
IB Psychology IA Criterion C: Analysis (6 Marks)
How do you write a clear analysis for your Psychology IA?
This section shows how well you can process and interpret your results. Examiners want to see that your data is clearly presented, statistically accurate, and connected back to your hypothesis.
What examiners look for
Correct use of descriptive statistics (e.g., mean, median, standard deviation) to summarize your data.
At least one appropriate inferential test that matches your design and data type.
Tables and graphs that are labeled, accurate, and clearly show the patterns in your findings.
A clear interpretation of results - what the numbers show and how they relate to your research question.
Logical links between your statistical results and the psychological theory you introduced earlier.
Common pitfalls
Listing results without explaining what they mean.
Choosing the wrong statistical test or failing to justify your choice.
Presenting data that’s more complex than your research requires.
Forgetting to connect your results to the hypothesis or variables.
How to reach the top band in Criterion C (6/6)
Present results visually where possible - tables and graphs make trends easy to see.
Report both descriptive and inferential results clearly (e.g., t(18) = 2.45, p<0.05).
Explain what the statistics mean before linking them to the theory.
Keep this section objective and focused on evidence - save opinions for your evaluation.
A clear analysis shows understanding. By the end of this section, the reader should know exactly what your results reveal about your research question.
IB Psychology IA Criterion D: Evaluation (6 Marks)
How should you evaluate your findings?
This section assesses how well you reflect on your results, link them back to theory, and recognize what your investigation did well - and where it could be improved.
What examiners look for
Clear links between your findings and the background theory or original study.
A balanced discussion of strengths and limitations in your design, sample, and procedure.
Justified modifications that address key limitations and explain how they would improve validity or reliability.
A conclusion that answers your research question directly, while acknowledging the study’s limits.
Common pitfalls
Listing every possible limitation instead of focusing on those that truly affected the outcome.
Suggesting improvements that aren’t realistic or clearly justified.
Failing to connect findings back to the psychological theory.
Ending abruptly without a clear, evidence-based conclusion.
How to reach the top band in Criterion D (6/6)
Focus on depth over quantity - choose two or three strong evaluation points and explain them well.
Link each limitation to a corresponding improvement, showing clear reasoning.
Make your conclusion specific and data-driven, not just a summary.
Keep the tone reflective, not apologetic - your goal is to show understanding, not perfection.
Good evaluation ties everything together. It shows that you can think critically about your results, recognize their limits, and still draw a confident, defensible conclusion.
Final Checklist: Before You Submit Your Psychology IA
Use this quick review to make sure your IB Psychology IA meets every criterion. Read it once through before finalizing your draft - it’s the fastest way to catch easy-to-fix details.
Criterion A: Introduction
Have you clearly stated your aim and explained why it’s worth investigating?
Did you include a short, relevant theory or model that connects to your study?
Are your independent and dependent variables defined and measurable?
Have you written both a research and a null hypothesis that follow logically from your aim?
Criterion B: Exploration
Does your research design suit your question?
Is your sample described clearly, with details on who participated and how they were chosen?
Have you explained your controlled variables and how you maintained them?
Are your materials and procedure clear enough that someone else could replicate the study?
Did you follow and mention all relevant ethical guidelines?
Criterion C: Analysis
Are your descriptive statistics accurate and easy to interpret?
Have you used at least one appropriate inferential test and reported it correctly?
Do your tables or graphs clearly show patterns or differences?
Have you explained what the results mean in relation to your hypothesis?
Criterion D: Evaluation
Did you link your findings back to the theory you introduced earlier?
Have you discussed two or three key strengths and limitations in depth?
Are your improvements realistic and well-justified?
Does your conclusion answer the research question directly?
When each of these boxes is ticked, your IA will read as clear, logical, complete - and ready for submission.
FAQ: IB Psychology IA
Do SL and HL students have different IAs?
No - the task and criteria are exactly the same. The only difference is weighting: it counts for 25% of your final grade at SL and 20% at HL.
How long should the Psychology IA be?
Your final report should be between 1,800 and 2,200 words. Anything beyond that won’t be marked, so keep your writing focused and concise.
Do I have to collect my own data?
Yes. The IA requires you to conduct your own simple experiment and collect your own data, usually by replicating a classic psychological study with one small change.
What statistical test should I use?
It depends on your research design and type of data. Most students use a t-test or Mann-Whitney U test, but choose what best fits your experiment - your teacher or supervisor can confirm if your choice makes sense.
Can I do my IA on any topic?
You can choose from a wide range of topics as long as it’s linked to an approved study and follows IB ethical guidelines. Avoid anything sensitive or invasive.
Do I need to include a bibliography?
Yes - you must include full citations for all sources you reference, using a consistent format such as APA or MLA.
Need Help With Your IB Psychology IA?
Whether you’re finalizing your draft or still figuring out how to start, our team can help you get your Psychology IA where it needs to be.
We offer three levels of support depending on where you are in the process:
One-off IA Review - Get detailed, criterion-based feedback on your draft from IB Psychology experts. You’ll know exactly where to refine and how to improve before submitting.
Draft Review + Feedback Session - Combine a full written review with a one-on-one session. We’ll walk through your IA together, clarify examiner expectations, and help you make targeted improvements.
IA Start (Brainstorm & Plan) - Haven’t started yet? We’ll help you choose a solid experiment idea, build a research question, and map out a clear structure that aligns with the IB criteria.
