Watch out
Choosing the larger standard deviation as more consistent.
Scottish National 5 Mathematics
National 5 Maths Standard deviation
Calculate or determine standard deviation and interpret it as a measure of spread.
Formula reference
Check the National 5 rules and formulae linked to this topic.
Which method?
Match exam clues to a suitable method.
Before you start
- Enter every data value accurately or complete the deviation table.
- Check the data list before calculating standard deviation and use the population value for the full data set.
- Read the command word, record the units or requested form, and make the final answer match it.
Explanation
Standard deviation is an assessed part of Scottish National 5 Mathematics in the statistics area. Calculate or determine standard deviation and interpret it as a measure of spread.
Enter every data value accurately or complete the deviation table.
Use the population standard deviation expected for the full data set.
Round as instructed and interpret in context.
The interactive bank below mixes direct skills, reverse questions, interpretation and contextual reasoning rather than repeating one number pattern.
Key formulae and rules
- A smaller standard deviation means values are generally closer to the mean.
Check
Check the calculation, then state what the result means for the named data or model rather than treating an estimate as exact.
Exam tip
Quote the relevant statistic or model value, then interpret it in the context of the named data.
Calculator tip
Check the data list before calculating standard deviation and use the population value for the full data set.
Worked examples
Worked example 1
Standard deviation worked example
Set A has standard deviation 2.1 and set B has 5.8. Which is more consistent?
- Consistency means values are less spread out.
- Set A has the smaller standard deviation.
Answer: Set A is more consistent.
Watch out
- Choosing the larger standard deviation as more consistent.
- Giving an interpretation without naming the data set.