Scatter Plot vs Line Graph: Which One Should You Use?
Both plot points on an XY plane, and the difference comes down to one question: is your x-axis time, or is it another measurement?
Line graph: change over an ordered axis
Use a line graph when the x-axis has a natural order — usually time. Connecting the points implies "this became that", which is only true when the order is meaningful.
Line graphs are excellent at showing trend, seasonality and the crossing point between two series.
Scatter plot: relationship between two variables
Use a scatter plot when both axes are measurements and there is no inherent order — ad spend vs conversions, height vs weight, price vs demand.
Leaving the points unconnected is the point: the cloud’s shape reveals correlation, clustering and outliers.
Add a least-squares trend line to quantify the direction, but remember that correlation is not causation.
How FastChart decides for you
If the first column looks like dates, years, quarters, months or weekdays, you get a line graph.
If both columns are plain numbers, you get a scatter plot.
Either way, one click on the chart type bar overrides the guess.
Try it with this data
Two numeric columns with no time axis — a scatter plot with a trend line.
Frequently asked
- Can I connect the points on a scatter plot?
- Only if the points have a meaningful order, such as successive measurements of the same object. Otherwise the line implies a sequence that does not exist.
- What is a bubble chart?
- A scatter plot with a third variable encoded as point size. Use it when you need to add magnitude to a relationship.
- Should a line graph axis start at zero?
- Not necessarily. Line graphs show change, so a truncated axis is acceptable if the range is labelled clearly. Bar charts, which encode value by length, must start at zero.
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