Research Methods and Measurement
Why Method Matters
From claim to evidence
In applied psychology, good intentions are not enough. Decisions should rest on evidence that is reliable, valid, and relevant to the target population.
Measurement concepts
Common methods
| Method | Strength | Limitation |
|---|---|---|
| Survey | Efficient for attitudes and self-reports | Can be distorted by response bias |
| Observation | Captures actual behavior | Observer bias can occur |
| Experiment | Supports causal inference | May be difficult in natural settings |
| Case study | Rich detail about a person or group | Limited generalizability |
Good practice
Always ask: Who was studied? How was the variable measured? What alternative explanations remain?
Which feature most strongly supports a causal conclusion?
Experiments improve causal inference by manipulating an independent variable and comparing outcomes.
Correct answer: An experiment with manipulation and control
What is an operational definition?
For example, stress might be operationalized through a questionnaire score or cortisol level.
Correct answer: A precise way of measuring or describing a concept in observable terms.
Statistics in Context
Interpreting results
Statistics do not prove truth on their own. They help estimate patterns, effect sizes, and uncertainty, which must then be interpreted in context.
Reading a study critically
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1
Identify the sample and setting.
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2
Check how key variables were measured.
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3
Look for controls or comparison groups.
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4
Examine effect size and practical significance.
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5
Consider limitations and possible confounds.
Why can a measure be reliable but not valid?
A measure can produce stable results while still failing to capture the intended construct.
Correct answer: It is consistent but may still measure the wrong thing
Give one reason why survey results can be misleading.
Any one valid limitation is acceptable.
Correct answer: Response bias, poor sampling, vague questions, or social desirability effects.