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Detect Outliers

Analyse > Detect outliers... highlights numeric values that sit far from the rest of their column, painting each flagged cell orange so unusual readings stand out.

Methods

  • IQR (interquartile range) - flags cells outside [Q1 - k*IQR, Q3 + k*IQR]. The usual k is 1.5.
  • Z-score (standard deviations) - flags cells more than k standard deviations from the mean. The usual k is 3.

Tick the columns to scan (numeric columns are pre-selected) and set k, then press Detect. Columns with fewer than four numbers are skipped.

What Detect does

Choose under When done:

  • Highlight outlier cells - paints each flagged cell orange. This is per tab and session-only: it never changes the data, only how it is shown, and Clear highlight removes it. Manual colour marks, conditional colours, and validation highlights all take priority over the orange.
  • Add an is_outlier column - appends a boolean is_outlier column that is true for every row holding at least one flagged value. This is a real, undoable edit (Ctrl+Z) you can save, sort, or filter on.

Stepping through flagged cells

With Highlight chosen, F10 jumps to the next flagged cell and Shift+F10 to the previous one, wrapping at the ends, with a Problem 3 of 27 counter in the status bar. The same keys also cover data validation violations, and rows hidden by the current filter are skipped.

Command line and assistant

Also available as octa --outliers (see the --outliers reference) and as the detect_outliers MCP / assistant tool.