Psychology IA Experimental Design Guide

Act as an IB Psychology tutor and research methods expert. Help me design and write my Psychology Internal Assessment: 1. **Choosing a Study to Replicate**: Select a published study suitable for replication — it must use a simple experimental design (independent measures, repeated measures, or matched pairs) and be ethically feasible for student research 2. **Operationalizing Variables**: Define your independent variable (IV) and dependent variable (DV) clearly and measurably. Ensure the DV produces quantitative data suitable for inferential statistics 3. **Experimental Design Decisions**: - Independent measures vs. repeated measures — justify your choice - Controlling confounding variables (standardized instructions, counterbalancing) - Sampling method: opportunity, random, stratified — explain selection and acknowledge limitations 4. **Ethical Guidelines**: Apply BPS/APA ethical principles: - Informed consent (written form required) - Right to withdraw at any time - Debriefing after participation - Confidentiality and anonymity - No deception without justification and ethical review 5. **Data Collection and Analysis**: - Descriptive statistics: mean, median, standard deviation - Inferential statistics: Mann-Whitney U test (independent measures) or Wilcoxon signed-rank test (repeated measures) - Significance level: $p < 0.05$ — explain what this means - Calculate and interpret your test statistic 6. **Report Structure**: Follow the IB IA format: - Introduction (background, aim, hypothesis — directional or non-directional) - Exploration (method: design, participants, materials, procedure) - Analysis (descriptive stats, inferential stats, interpretation) - Evaluation (strengths, limitations, modifications, further research) **Key terminology:** - Null hypothesis ($H_0$), alternative hypothesis ($H_1$) - Type I error (false positive), Type II error (false negative) - Effect size, statistical significance **Common mistakes to avoid:** - Choosing a study that is too complex to replicate ethically - Failing to operationalize variables precisely - Using the wrong statistical test for your design - Not linking back to the original study in your evaluation **IB Tip:** The IA is worth 25% of your grade. Focus on clear methodology and thorough evaluation — examiners value critical thinking over complex designs. **My IA question:** [DESCRIBE YOUR STUDY IDEA OR PASTE YOUR CURRENT IA DRAFT]