In one line: A psychological idea can be studied only once it has been given a precise, observable definition.
Empathy cannot be seen or weighed. It is a construct: an idea inferred from what people do and say.
To study it, a researcher must operationalise it. One team counts how often a child comforts a classmate. Another uses a questionnaire filled in by parents. A third asks children to name the emotions on photographs of faces. Each has turned the same construct into a different variable.
Remember: Different operational definitions can give different answers to the same question.
Free preview
This is the free notes preview
You're reading the free notes. Aimnova Pro unlocks the full study experience — and you can try it with your first topic free to keep:
- FlashcardsLock in vocabulary and key terms with spaced repetition.
- Practice questionsAnswer exam-style questions and get instant AI marking.
- Mock exams & past-paper vaultSit full mocks and see exactly how examiners award marks.
- Personalised study planA daily plan built around your exam date and weak areas.
Key idea: The choice of measure decides what kind of data a study has, and what can be done with it.
| Quantitative | Qualitative | |
|---|---|---|
| What it gives | Numbers that can be analysed statistically | Words, themes and meanings |
| Example | Faces named correctly out of ten | A child's account of why a friend was upset |
| Analysed by | Descriptive and inferential statistics | Content analysis: sorting text into themes |
| Limit | May reduce a rich idea to one number | Depends on the researcher's interpretation |
Where the data come from
Self-reported data
What people say about themselves or others: questionnaires, interviews, ratings.
Open to social desirability and to the limits of self-knowledge.
Empirical data
What is observed or recorded: counts of behaviour, reaction times, brain scans.
Less open to what people wish to say, but it still has to be interpreted.
Self-reported · Empirical
Mixed data and triangulation: Many studies collect both kinds of data.
When different methods give the same answer (triangulation of methods), the finding is more credible.
Practice with exam-style questions
Answer exam-style questions and get AI feedback that shows you exactly what examiners want to see in a full-marks response.
Key idea: Most measurement in psychology is indirect, and much of it depends on memory.
Direct measure
- The behaviour itself is recorded
- Times a child comforts a classmate
- Validity is easier to defend
Indirect measure
- A sign of the construct is recorded
- Brain activity while viewing faces
- An inference is needed from sign to construct
A brain scan illustrates the point. An MRI scanner measures changes in blood flow. That the activity reflects "empathy" is an interpretation, however precise the image.
Time adds a second distinction. A retrospective approach asks people to report what happened in the past. A prospective approach identifies people first and records events as they unfold. Prospective data avoid errors of memory but take longer to collect.
Exam tip: For each variable in a study, make two checks.
Self-reported or empirical? Recorded at the time or recalled?
Key idea: A statistical test reduces the risk of a wrong conclusion. It never removes it, and the two risks pull against each other.
Type I error
- A false positive
- The study reports an effect that does not exist
- More likely when many tests are run
Type II error
- A false negative
- The study misses an effect that does exist
- More likely with a small sample or a crude measure
A result is called statistically significant when the probability of getting it by chance is below an agreed level, usually 5 in 100. At that level, about one in twenty tests of an effect that does not exist will still come out significant.
Making the level stricter reduces type I errors and increases type II errors. Neither can be driven to zero, which is why replication matters more than any single result.
Remember: A crude measure makes real effects harder to find.
Poor measurement is a cause of type II errors.
Feeling unprepared for exams?
Get a clear study plan, practice with real questions, and know exactly where you stand before exam day. No more guessing.
How this is asked: In IB Psychology your class runs four small studies of its own, called class practicals: an experiment, an interview, an observation and a survey. Paper 2 asks about the ones your class ran, so keep a short note of each: aim, what you did, who took part, what you found, and the ethics.
Measurement is one of the four concepts offered in the 15-mark question on an unseen study, and it is asked in 4 marks about the class practical.
It also underlies the 15-mark essay that asks you to evaluate how something is measured.
The pattern
- Name the construct and its operational definition, for each variable.
- Classify the data: self-reported or empirical, direct or indirect, recalled or recorded.
- Ask what else the measure could reflect.
- Connect the measure to a second concept: bias or causality.
- Judge the conclusion, and say what would measure the construct better.
The trap: significance as a defence: A significant result does not show that the measures were sound.
A poor measure can produce a significant difference in something other than the construct.
Discuss the following study with reference to two or more of the following concepts: bias, causality, measurement and/or responsibility.
Researchers wanted to know whether children who read more fiction have more empathy. They asked the parents of 200 eight-year-olds to estimate how many storybooks their child had read, or been read, in the past year. Each child was then shown ten photographs of faces and asked to name the emotion; the number correct was the empathy score. Children whose parents reported more books scored higher. The difference between the highest and lowest thirds was statistically significant. The researchers concluded that reading fiction develops empathy.
Model answer plan
See the mark-by-mark plan — for / against / judgement, with marking guidance — in study mode.