Learning Objectives
Experimental design
- Define the aim of a study.
- State a research and null hypothesis of a study (HL only).
- 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).
- 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 procedures
- 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.
Evaluation of research
- 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).
- Apply an appropriately chosen statistical test (for example, Wilcoxon matched‑pairs signed‑ranks test, Mann–Whitney U test, sign test, chi‑squared test) in order to determine the level of significance of data (HL only).
Supplementary Readings
