WJEC A-Level Psychology 601-5719-7
Psychology Past to Present — The Five Approaches
Contemporary Debates
Principles of Research and Application of Research Methods
Mathematical Requirements for Psychology (Appendix A: AS Unit 2 and A2 Unit 4)
Addictive BehavioursAddictive
Autistic Spectrum BehavioursAutistic spectrum
Bullying BehavioursBullying
Criminal BehavioursCriminal
SchizophreniaSchizophrenia
StressStress
Controversies in Psychology
Applied Research Methods
Principles of Research and Application of Research Methods
Descriptive Statistics: the range, the standard deviation and choosing a measure
- 3 things to know
- AS Unit 2
Overview
When the mode is the only measure available, the range and the standard deviation calculated and compared, and choosing a measure to suit the level of measurement.
What you need to know
Answer each one before you reveal it.
What does a measure of dispersion tell you?
Give one problem with using the mode.
Questions from this subtopic
Each one with the model answer underneath.
- 1
When is the mode the only measure of central tendency available?
Model answer
When the data are nominal, because categories can be counted but not ordered or averaged.
- 2
Give one problem with using the mode.
Model answer
A set of data may have two modes or none at all, and the mode can shift a long way when only a few scores change.
- 3
What does a measure of dispersion tell you?
Model answer
How spread out the scores are around the central value, and therefore how varied or consistent the participants were.
- 4
How is the range calculated?
Model answer
By subtracting the lowest score in the set from the highest.
- 5
The fastest participant completed a task in 12 s and the slowest took 47 s. State the range.
Model answer
The range is 35 s.
- 6
Why is the range a crude measure of dispersion?
Model answer
It uses only the two most extreme scores, so a single unusual participant can make a tightly clustered set of data look widely spread.
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