# Why do we differentiate between log linear vs. exponential time series

#### dreamchef

##### New Member
Given by definition for a function to be linear on a log plot, it must be exponential (bc log_a(e^x)=x), why do we differentiate between log linear and exponential things?

#### katxt

##### Well-Known Member
Most of the theory is based on straight lines and equal errors. Often a situation is not like this, but it becomes so if we log the y's. Then we can use the standard techniques on the transformed data.