IB Psychology/Internal Assessment/Simple Experimental Study

Standard Level Experimental StudyEdit

Every student that does Standard Level psychology must complete a simple experimental study, which counts for 25% of the final grade. The experimental study can be undertaken in groups by up to four students. More than one group is allowed to research the same aim; however, the actual assessment must be written individually.

Time AllocationEdit

It is recommended that each student spends at least 30 hours on the experiment. This time includes the time for the teacher to explain to students the requirements of the internal assessment, time to consider the psychology course ethical guidelines, class time for students to work on the internal assessment component, time for consultation between the teacher and each student, and time to review and monitor progress, and to check authenticity.

Ethical GuidelinesEdit

The ethical guidelines that must be followed for the assessment are as follows:

  • Any experimental study that creates anxiety, stress, pain or discomfort for participants must not be permitted.
  • Any experimental study that involves unjustified deception, involuntary participation or invasion of privacy, including the inappropriate use of information and communication technology (ICT), email and the internet, must be avoided. There may be rare occasions when such infringements cannot be avoided, in which case the approval of other experienced psychologists should be sought before proceeding.
  • All participants must be informed before commencing the experimental study that they have the right to withdraw at any time. Pressure must not be placed on any individual participant to continue with the investigation beyond this point.
  • Each participant must be informed of the aims and objectives of the research and must be shown the results of the research.
  • Young children should not be used as participants. Experimental studies involving children need the written consent of parent(s) or guardian(s). Students must ensure that parents are fully informed about the implications for children who take part in such research. Where an experimental study is conducted with children in a school, the written consent of the teachers concerned must also be obtained.
  • Participants must be debriefed and given the right to withdraw their own personal data and responses. Anonymity for each participant must be guaranteed.
  • Teachers and students must exercise the greatest sensitivity to local and international cultures.
  • Students must avoid conducting research with any adult who is not in a fit state of mind and cannot respond freely and independently.
  • If any participant shows stress and/or pain at any stage of an experimental study, the investigation must finish immediately, and the participant must be allowed to withdraw.
  • Non-human animals must not be used for experimental study.
  • All data collected must be kept in a confidential and responsible manner and not divulged to any other person.
  • Students must regard it as their duty to monitor the ways in which their peers conduct research, and to encourage public re-evaluation of any research that contravenes these guidelines.


Introduction to experimental research methodologyEdit

Knowledge and understanding of quantitative methods and statistical analysis of data is assessed through the reporting of one simple experimental study. In this context students should be able to:

  • explain what is meant by the experimental method
  • explain the use of quantitative research methods.

The experimental methodEdit

For the IB Diploma Programme psychology course the experimental method is defined as requiring:

  • the manipulation of one independent variable while other variables are kept constant
  • the measurement of the effect of the independent variable on one dependent variable.

Quasi-experimental studies examine the effect of a naturally occurring or pre-existing independent variable (for example, age, gender, ethnicity) not an independent variable that is manipulated by the researcher. Therefore, in quasi-experimental studies the participants cannot be randomly allocated to conditions but are assigned to conditions on the basis of the pre-existing independent variable. In correlational studies a relationship is sought between two variables, but neither of these variables is manipulated by the researcher. Consequently cause and effect cannot be inferred from the findings of correlational studies.

The use of quantitative research methodsEdit

Psychologists use quantitative methods to investigate areas of study where it is possible to test hypotheses under rigorous conditions. Experiments can take place in the laboratory or in the field. The aim is to be able to establish a cause and effect relationship through the use of descriptive as well as inferential statistics, allowing the researcher to determine the significance of the results.

Experimental research learning outcomesEdit

Experimental designEdit

  • Define the aim of a study.
  • State the independent and dependent variable in an experiment.
  • State operational definitions of variables.
  • Describe potential confounding variables.
  • Explain the controls needed for an experiment (for example, maturation, contamination, placebo effect).
  • Explain effects of participant and researcher expectations and bias (including demand characteristics, expectancy effect, observer bias, Hawthorne effect).
  • Explain the use of single- and double-blind techniques.
  • Discuss the strengths and limitations of experimental designs (for example, independent samples, repeated measures, matched pairs, single participant).

Sampling proceduresEdit

  • Discuss sampling techniques appropriate to quantitative research (for example, random, opportunity, systematic, stratified).
  • Discuss how participants are allocated to experimental and control groups (for example, matched pairs, random allocation).
  • Explain the concept of representative sampling.Internal assessment

Evaluation of researchEdit

  • Discuss the concepts of internal and external validity.
  • Discuss conditions that increase a study’s reliability.
  • Apply descriptive statistics to analyse data (for example, mean, median, mode, range, standard deviation).
  • Distinguish between levels of measurement (including nominal, ordinal, interval, ratio).
  • Apply appropriate graphing techniques to represent data (for example, bar chart, histogram, line graph, frequency polygon).