Reading Scatter Plots and Correlations

Scatter plots (also called scatter diagrams or scatter graphs) occasionally appear in UCAT QR. They show the relationship between two numerical variables, with each data point plotted as a dot. While less common than tables or bar charts, scatter plot questions can be straightforward if you understand how to read them and identify patterns.

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Anatomy of a Scatter Plot

A scatter plot has:

• X-axis (horizontal): One variable (e.g., hours of study)
• Y-axis (vertical): Another variable (e.g., exam score)
• Data points: Each dot represents one observation (e.g., one student's hours of study and exam score)
• Optional line of best fit: A straight line drawn through the data to show the overall trend

Reading Individual Data Points

To find the values for a specific data point:

1. Identify the point
2. Read horizontally to the y-axis for the y-value
3. Read vertically down to the x-axis for the x-value

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Types of Correlation

Positive Correlation

As one variable increases, the other tends to increase. Points slope upward from left to right.

Example: Hours of study vs exam score — more study generally leads to higher scores.