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Cognitive Psychology
Measures of central tendency and dispersion
- 3 things to know
- Papers 1 and 3
Overview
Recall questions on choosing and calculating the mean, median and mode, the range, percentages, calculating and interpreting standard deviation, significant figures and order-of-magnitude checks, and normal, positively skewed and negatively skewed distributions.
What you need to know
Answer each one before you reveal it.
Why is standard deviation generally preferred over the range as a measure of dispersion?
Why might a researcher choose the median over the mean when summarising data?
Questions from this subtopic
Each one with the model answer underneath.
- 1
Why might a researcher choose the median over the mean when summarising data?
Model answer
The median is less affected by extreme values or outliers, making it more representative of central tendency in skewed distributions.
- 2
In what situation would the mode be the most appropriate measure of central tendency?
Model answer
The mode is most appropriate for categorical or nominal data, or when identifying the most common response is more meaningful than an average.
- 3
What is the mean as a measure of central tendency?
Model answer
The mean is the arithmetic average of a data set, calculated by summing all values and dividing by the number of values.
- 4
Describe how the mean is calculated.
Model answer
The mean is calculated by summing all values in the data set and dividing by the total number of values.
- 5
What formula is used to calculate the mean?
Model answer
Mean = sum of all values ÷ number of values.
- 6
Calculate the mean when sum of values = 470, number of values = 11.
Model answer
Mean = 470 ÷ 11 = 42.7.
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