1. Exploratory Data Analysis
1.3. EDA Techniques
1.3.3. Graphical Techniques: Alphabetic
1.3.3.26. Scatter Plot

1.3.3.26.6.

Scatter Plot: Exponential Relationship

Scatter Plot Showing Exponential Relationship

Discussion

Note that a simple straight line is grossly inadequate in describing the relationship between X and Y in this plot of the CHWIRUT2.DAT data set. A quadratic model would prove lacking, especially for large values of X. In this example, the large values of X correspond to nearly constant values of Y, and so a non-linear function beyond the quadratic is needed. Among the many other non-linear functions available, one of the simpler ones is the exponential model

\[ Y_{i} = A + B e^{CX_{i}} + E_{i} \]

for some A, B, and C. In this case, an exponential function would, in fact, fit well, and so one is led to the summary conclusion of an exponential relationship.