SupportStandard Deviation Calculator with Outlier Detection
Calculate population and sample standard deviation, variance, and range. Includes automatic outlier detection and data visualization using histograms and bar charts.
Input Data
Distribution Histogram
Quartiles & Range
Outlier Detection
All Values (Sorted)
What is Standard Deviation?
Standard deviation is a measure of the amount of variation or dispersion of a set of values. A low standard deviation indicates that the values tend to be close to the mean, while a high standard deviation indicates that the values are spread out over a wider range.
Population SD
Used when the data set includes the entire group you are interested in (the entire population).
Sample SD
Used when the data set is a subset of a larger population. This is the most common measure used in research.
Detecting Outliers
Outliers are data points that differ significantly from other observations. This tool uses the Tukey method (1.5 × IQR) to identify outliers:
- Q1 (First Quartile): The 25th percentile of the data.
- Q3 (Third Quartile): The 75th percentile of the data.
- IQR (Interquartile Range): Q3 - Q1.
- Outlier: Any value smaller than Q1 - 1.5 × IQR or larger than Q3 + 1.5 × IQR.
Visualization Options
Data can be visualized using either a Histogram (to see the frequency distribution) or a Bar Chart (to see individual value distributions). Highlighting outliers helps in identifying data entry errors or unique phenomena in your dataset.
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