When points are grouped closely together in a horizontal line on a scatterplot, it typically indicates a strong negative correlation or strong positive correlation, depending on the direction of the line.
- If the line is slanting downward from left to right, it indicates a strong negative correlation, meaning that as one variable increases, the other variable decreases.
- If the line is slanting upward from left to right, it indicates a strong positive correlation, meaning that as one variable increases, the other variable also increases.
If the points are exactly horizontal (i.e., they have the same y-value), this suggests that there is no correlation, as changes in the x-variable do not affect the y-variable at all.
In summary:
- Horizontal line with a downward slope: Strong negative correlation.
- Horizontal line with an upward slope: Strong positive correlation.
- Perfectly horizontal line: No correlation.
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