What is a scatter plot?

A **scatter plot** is a type of data visualization that uses Cartesian coordinates to display values for two different variables for a set of data. Each point on the scatter plot represents an individual data point, with its position determined by the values of the two variables: - **Horizontal Axis (X-axis):** Represents one variable. - **Vertical Axis (Y-axis):** Represents the other variable. ### Purpose of a Scatter Plot Scatter plots are primarily used to: 1. **Identify Relationships:** Determine if there is a correlation or association between the two variables. For example, you might use a scatter plot to see if there's a relationship between hours studied and exam scores. 2. **Detect Patterns or Trends:** Observe patterns such as positive correlation (as one variable increases, so does the other), negative correlation (as one variable increases, the other decreases), or no correlation. 3. **Spot Outliers:** Identify data points that do not fit the general pattern of the data, which can be important for data analysis and quality control. ### Example Imagine you want to explore the relationship between the number of hours students study and their scores on a test. You collect data from 30 students: - **X-axis:** Hours Studied - **Y-axis:** Test Scores Each student is represented as a point on the plot. If the points generally trend upwards from left to right, this suggests a positive correlation—indicating that more study hours are associated with higher test scores. ### Additional Features - **Trend Line:** Often, a line of best fit (trend line) is added to visually represent the overall direction of the data. - **Multiple Variables:** While a basic scatter plot displays two variables, you can represent additional variables using different colors, sizes, or shapes of the data points. ### When to Use a Scatter Plot Scatter plots are ideal when you want to: - Explore or demonstrate the relationship between two quantitative variables. - Analyze the distribution and identify patterns or anomalies in the data. - Present data in a clear and visually appealing manner for reports or presentations. ### Comparison to Other Plots Unlike bar charts or histograms, which are typically used for categorical or single-variable data, scatter plots are specifically designed to show the relationship between two continuous variables. --- **Visual Example:** Imagine the following simple scatter plot: ``` Test Scores | 100 | * | * 80 | * | * 60 | * |* |------------------- 1 2 3 4 5 6 Hours Studied ``` Each "*" represents a student's hours studied and their corresponding test score. The upward trend suggests that generally, more hours studied are associated with higher test scores. Scatter plots are powerful tools in statistics, research, finance, engineering, and many other fields for data analysis and decision-making.