Scatter plot maker
Paste two columns, x and y, straight from a spreadsheet. The points are plotted and a trend line is one click away.
Two columns: x on the left, y on the right. Paste them straight from a spreadsheet.
Drawing…
| Points | 12 |
|---|---|
| Line of best fit | y = 6.401x + 45.1457 |
| Correlation r | 0.9821 |
| r² | 0.9645 |
How to use it
- Step 1Paste two columns: x on the left, y on the right. A header row is recognized and left out of the points.
- Step 2Tick “Line of best fit” if your assignment asks for a trend line — the equation, r and r² are printed with it.
- Step 3Download the plot as a PNG or an SVG, or make a link so someone else can open the same points.
What a scatter plot is for
A scatter plot asks one question: when x goes up, what does y do? Each row of your table becomes one point, and the shape of the cloud is the answer. A cloud sloping up is a positive relationship, one sloping down is negative, and a shapeless blob means the two measurements have little to do with each other.
The shape matters as much as the slope. A curve that bends is a real relationship that a straight line will describe badly; a cloud that fans out as x grows means the spread of y depends on x, which is worth saying out loud in a write-up. Both are visible in a scatter plot and invisible in a correlation coefficient.
The line of best fit, r and r²
The line drawn here is the least-squares line: the straight line that makes the total squared vertical distance to the points as small as possible. Its equation is printed on the chart in the form y = mx + b, so it can go straight into homework.
Next to it are two numbers. Pearson's r runs from −1 to 1 and says how tightly the points hug a straight line: −1 and 1 are perfect lines, 0 is no linear relationship at all. r² is r multiplied by itself, read as the share of the variation in y that the line accounts for — an r of 0.8 gives an r² of 0.64, so about two thirds of the movement in y follows the line and a third does not.
Neither number says anything about cause. Ice cream sales and sunburn rise together every summer; the line is real, the causation is the sun. A scatter plot is evidence of a pattern and an invitation to explain it.
Data that does not fit two columns
Rows where either number is missing are skipped, and the page says how many were skipped rather than shifting the remaining values up — a point needs both an x and a y to exist. If your x values are dates or categories rather than numbers, a line graph is the chart you want instead.
Questions and answers
How do I make a scatter plot from two columns?
Copy both columns from your spreadsheet and paste them into the box. The left column becomes x, the right becomes y, and the points appear immediately.
How do I add a trend line?
Tick “Line of best fit”. The least-squares line is drawn across the plot with its equation, the correlation r and r² written next to it.
What does r mean?
How close the points are to a straight line, from −1 (perfectly downward) through 0 (no linear pattern) to 1 (perfectly upward). It says nothing about whether one thing causes the other.
Should I join the points?
Only if the x values are a sequence — times, trials, days — and the order means something. For two measurements of the same subjects, leave the points loose; joining them draws a relationship that is not there.