Relationship between Two Variables Shown in Line Diagram

Introduction:
In statistics, we often deal with two or more variables and their relationship. To understand the relationship between two variables, we need to analyze the data and represent it in a graphical form. One such graphical representation is a line diagram.

Definition:
A line diagram is a graphical representation of data points that are connected with a line. It is used to show the relationship between two variables, where one variable is plotted on the x-axis (horizontal axis) and the other variable is plotted on the y-axis (vertical axis).

Example:
Suppose we want to analyze the relationship between the temperature and the sales of ice cream in a particular region. We collect the data for the temperature and the sales of ice cream for the past month. The data is given below:

Temperature (°C) Sales (units)
20 50
22 65
24 80
26 95
28 110
30 125

To represent this data in a line diagram, we plot the temperature on the x-axis and the sales on the y-axis. The data points are then connected with a line, as shown in the figure below:


Interpretation:
From the line diagram, we can see that there is a positive relationship between the temperature and the sales of ice cream. As the temperature increases, the sales of ice cream also increase. This relationship is represented by the upward slope of the line. We can also estimate the sales of ice cream for a given temperature by drawing a perpendicular line from the temperature on the x-axis to the line and then reading the sales from the y-axis.

Conclusion:
Line diagrams are an effective way to represent the relationship between two variables. They help us to visualize the relationship and make predictions based on the data.