Scatter-Bubble Component
The Scatter-Bubble component plots individual data points in a two-dimensional space defined by two numeric fields (scatter mode) or three numeric fields where the third controls point size (bubble mode). It is the primary component for identifying correlations, clusters, and outliers in project data.
Scatter vs. Bubble mode
| Mode | Axes | Point size | Best for |
|---|---|---|---|
| Scatter | X and Y numeric fields | Fixed size | Correlation analysis, outlier detection |
| Bubble | X and Y numeric fields | Proportional to a third numeric field | 3-variable relationship (e.g., cost × duration × risk score) |
Switch between modes in Properties → Chart type.
Data binding
| Property | Description |
|---|---|
| X axis field | Numeric field for the horizontal position. |
| Y axis field | Numeric field for the vertical position. |
| Size field | (Bubble mode only) Numeric field controlling the bubble radius. |
| Series / color field | Optional field to color-code points by category (e.g., discipline, contractor). |
| Label field | Optional field shown as a text label next to each point (e.g., Activity ID, document number). |
Axis options
| Option | Description |
|---|---|
| X and Y axis range | Auto-scale or fixed min/max. |
| Axis titles | Descriptive labels explaining what each axis represents. |
| Log scale | Enable logarithmic scaling for either axis when the value range spans orders of magnitude. |
| Zero line | Show/hide a line at zero on both axes. |
| Grid density | Major gridlines only, or major + minor. |
Trend lines
Overlay a trend line on the scatter to indicate the overall relationship direction:
| Type | Description |
|---|---|
| Linear | Straight-line least-squares regression. Equation and R² displayed optionally. |
| Polynomial | Polynomial curve (degree 2 or 3). |
| Moving average | Smoothed rolling average line. |
| Per-series | Separate trend lines per series (when a series field is configured). |
Reference bands and quadrant lines
Add horizontal or vertical reference lines to divide the chart into quadrants:
| Property | Description |
|---|---|
| Reference line (X or Y axis) | Fixed or field-bound value. |
| Quadrant labels | Label each of the four quadrants created by two reference lines (e.g., "High risk / Low duration"). |
| Quadrant fill | Subtle background color fill per quadrant. |
Quadrant visualisation is useful for risk matrix presentation (likelihood vs. impact) or performance quadrant analysis (low cost / high float, high cost / low float).
Density rendering
For large datasets (> 500 points) that would produce overlapping clutter:
| Option | Description |
|---|---|
| Point opacity | Reduce opacity (e.g., 30%) so overlapping points create visible density through color accumulation. |
| Density heatmap overlay | Replace individual points with a heatmap showing point concentration. Useful for very large datasets. |
| Jitter | Add a small random positional offset to points sharing identical coordinates. |
Bubble size options (Bubble mode only)
| Property | Description |
|---|---|
| Min bubble size | Minimum pixel radius regardless of value. |
| Max bubble size | Maximum pixel radius for the largest value. |
| Size scale | Linear or square root (square root is recommended for area-proportional perception). |
| Show size legend | Display a reference legend showing what bubble sizes correspond to. |
| Negative values | How to handle negative size field values: show as a different color, use absolute value, or hide. |
Zoom and pan (interactive mode)
In interactive outputs, the chart supports:
- Rectangular zoom — drag a box to zoom in.
- Scroll zoom — scroll wheel to zoom in/out.
- Pan — drag after zooming to navigate.
- Reset zoom — double-click or dedicated button.
Zoom state is reset when the report page reloads.
Good practice
- Always label axis titles so readers understand the units and dimensions without reading the chart caption.
- For bubble charts, include a size legend so readers can interpret bubble area.
- Use the series color field to add a third dimension of categorical context.
- Add quadrant lines when the goal is to classify points into four strategic zones.
Related
- Box Plot — statistical distribution by category
- Chart Component — histogram and standard scatter variants
- Advanced Charts — overview of all advanced chart types