How do you find a linear model?
For experimental data it may be appropriate to use linear regression.
On the other hand, for precise data you do not need linear regression.
If you have a number of experimentally generated data points that are subject to inaccuracies then you can use something like linear regression to generate a linear model that fits the data reasonably well. Many modern calculators have a linear regression capability.
On the other hand, if you are given precise data, you should be able to generate a model that fits the data exactly. For example, given points
from which we can derive the slope-intercept form: