standard deviation: meaning, definition, pronunciation and examples
C1+Formal, Technical, Academic
Quick answer
What does “standard deviation” mean?
A statistical measure that quantifies the amount of variation or dispersion of a set of data values around their mean (average). A low standard deviation indicates data points are close to the mean, while a high standard deviation indicates data points are spread out over a wider range.
Audio
Pronunciation
Definition
Meaning and Definition
A statistical measure that quantifies the amount of variation or dispersion of a set of data values around their mean (average). A low standard deviation indicates data points are close to the mean, while a high standard deviation indicates data points are spread out over a wider range.
Beyond statistics, it can metaphorically describe the degree of variability, unpredictability, or departure from a norm within any system, process, or group (e.g., "the standard deviation in performance across the team was concerning").
Dialectal Variation
British vs American Usage
Differences
No significant lexical or definitional differences. Pronunciation differs (see IPA). The abbreviation 'SD' is equally common. The term 'root-mean-square deviation' is a less common synonym used in both varieties.
Connotations
Identical technical connotations. In metaphorical/extended use, it carries the same connotation of measurable variability.
Frequency
Equally high frequency in academic, scientific, and technical contexts in both varieties due to the universality of statistics.
Grammar
How to Use “standard deviation” in a Sentence
The standard deviation of [NOUN PHRASE] is [VALUE].We calculated the standard deviation for [NOUN PHRASE].[NOUN PHRASE] has a standard deviation of [VALUE].Vocabulary
Collocations
Examples
Examples of “standard deviation” in a Sentence
verb
British English
- The data points deviate widely from the norm.
- We must account for how the results might deviate.
American English
- The measurements deviate significantly from the expected value.
- His method deviates from the standard protocol.
adverb
British English
- [No standard adverbial form in common use. 'Standard-deviationally' is not a word.]
American English
- [No standard adverbial form in common use.]
adjective
British English
- We need the standard-deviation value for the report.
- The standard-deviation calculation is crucial.
American English
- Look at the standard-deviation metric on the chart.
- They performed a standard-deviation analysis.
Usage
Meaning in Context
Business
Used in finance (e.g., investment risk analysis, volatility of stock returns), quality control (process variability), and HR (analysing performance metrics).
Academic
Ubiquitous in research papers across sciences, social sciences, and medicine to describe data spread; a core concept in statistics courses.
Everyday
Very rare in casual conversation. Might appear in discussions about test scores, weather patterns, or sports statistics among educated speakers.
Technical
The primary, precise statistical term used in data analysis, engineering, physics, psychology, and machine learning.
Vocabulary
Synonyms of “standard deviation”
Strong
Neutral
Vocabulary
Antonyms of “standard deviation”
Watch out
Common Mistakes When Using “standard deviation”
- Saying 'standard deviate' (incorrect noun form).
- Using 'standard deviation' interchangeably with 'variance' (variance is SD squared).
- Omitting 'the' (e.g., 'We calculated standard deviation' – should be 'the standard deviation').
- Mispronouncing 'deviation' with stress on 'de-' (correct stress is on '-a-' /ˌdiːviˈeɪʃən/).
FAQ
Frequently Asked Questions
No. Variance is the average of the squared differences from the mean. Standard deviation is the square root of the variance. Standard deviation is more commonly used because it is in the original units of the data.
For a population, it is the Greek letter sigma (σ). For a sample taken from a population, it is denoted by the letter 's'.
No. Because it is derived from squared differences (which are always positive or zero) and then square-rooted, the standard deviation is always a non-negative number (zero or positive).
Use 'population standard deviation' (σ) when your data includes every member of the group you're studying. Use 'sample standard deviation' (s) when your data is only a subset (a sample) of a larger population. The formula for 's' includes a correction (n-1 in the denominator) to provide a better estimate of the population parameter.
A statistical measure that quantifies the amount of variation or dispersion of a set of data values around their mean (average). A low standard deviation indicates data points are close to the mean, while a high standard deviation indicates data points are spread out over a wider range.
Standard deviation is usually formal, technical, academic in register.
Standard deviation: in British English it is pronounced /ˌstændəd ˌdiːviˈeɪʃən/, and in American English it is pronounced /ˌstændərd ˌdiviˈeɪʃən/. Tap the audio buttons above to hear it.
Phrases
Idioms & Phrases
- “[No common idioms directly associated with this technical term]”
Learning
Memory Aids
Mnemonic
Think of a group of students taking a test. If everyone scores close to 85 (the MEAN), the scores have a small 'standard deviation' – they've all 'deviated' only a little from the 'standard' (average). If scores range from 50 to 100, the 'standard deviation' is large, meaning they 'deviated' a lot from that 'standard' score.
Conceptual Metaphor
VARIABILITY IS PHYSICAL SPREAD/DISTANCE. Data is metaphorically conceptualized as objects in space; standard deviation is the 'average distance' of these objects from the central point (the mean).
Practice
Quiz
What does a 'low standard deviation' in a dataset most directly indicate?