The method matters
Quartiles have several calculation conventions. We use type 7 linear interpolation, locating h = (n − 1)p in zero-indexed sorted data. Check the method when comparing other software, particularly with small samples.
POSITION / TRANSPARENT METHOD
Quartiles and IQR
Summarise the middle of the distribution with a clearly stated method.
This tab’s workspace
Interactive examples
Predefined synthetic data only. The link shares the example, never your numbers or metadata. Loading an example replaces current fields.
01Enter your data
Example⇧ Import or paste a table
Choose options explicitly. Missing cells are flagged, not skipped.
Download an example CSV ↓
Review the table before importing
Uses the columns and decimal format selected above. Row numbers refer to the parsed table including the header; completely blank rows may already have been ignored. No correction or exclusion is automatic.
At most 80 notices are displayed; every row is checked.
The report retains the original table, edits and excluded rows. It contains data: share deliberately. This is an editable local trail, not a certification.
Compare table columns
Select up to 8 numeric columns. Every selected cell must be valid; no individual missing values are removed. This is a descriptive comparison, not a test between groups.
Resume an analysis from a file
Open a .json file exported by StatNivo. Replaces current data and recalculates in this calculator; nothing is uploaded.
Raw data: up to 10,000 values per series.
Temporary storage is off unless you select the option.
02Read your result
Loading the local calculator…
Export, save and share
Undefined values: empty cells. No additional rounding in CSV files. CSV headings use stable English identifiers for software compatibility.
Temporary storage is off unless you select the option. Optional sessionStorage, off by default. Keeps text, table and settings across tools and languages in this tab. Browser session restoration can retain it. Use “Delete saved data” on a shared device. Nothing is uploaded.
LOOK BEYOND THE MEAN
The shape of your data
Scroll the chart horizontally to read the full scale. Frequencies are also available in the table.
Read frequencies as a table
How we get the result
Inspect observations and deviations
50 rows per page. Original row positions are retained; CSV includes all observations.
UNDERSTAND, DON’T JUST CALCULATE
The method in practice
IQR = Q₃ − Q₁ · fences: Q₁ − 1.5 IQR; Q₃ + 1.5 IQR
A simple example
For 1, 2, 3, 4, 5, 6, 7, 8, Q1 = 2.75, median = 4.5 and Q3 = 6.25. IQR is 3.5. Box plot whiskers end at the most extreme observations still inside the 1.5 IQR fences, not at the theoretical fences themselves.
Flagging is not deletion
Observations outside the fences are flagged as potential outliers. We do not remove them or conclude that they are wrong. They may reflect the real process, an error or a mixture of populations: context is essential.
Practical checks before using a result
Sample or population?
For 2, 4, 4, 4, 5, 5, 7, 9 the population SD is 2; sample SD is √(32/7) ≈ 2.13809. Choose the population formula when describing the full population of interest, not because the number is smaller.
Standard deviation or standard error?
Standard deviation describes the spread of observations. The usual standard error of the mean is sample SD / √n under independent sampling with finite variance. For sample SD 10 and n = 25, SEM = 2. Repeated dependent readings do not automatically count as 25 independent measurements.
Importing from Excel without shifting pairs
Paste the entire table, select its real delimiter and header, then preview it. In decimal-comma data, use a semicolon or tab as the column delimiter. If Y is missing in row 3, fix that row rather than moving row 4 up.