# Solution Exercise 8

There are multiple reasons why the model for the conductivity of the earth below an array of electrodes is likely to deviate from reality. Four reasons are:

- Measurement physics: electrical conduction is described by a diffusion equation; small-scale heterogenieties are often not captured by these equations
- Parameterization and regularization: as part of the inverse problem, the mathematics describing electrical flow is discretized, leading to some errors, and regularization is added to the inverse problem that often serves to smooth the final image
- Limited resolution: there is insufficient information in the data to capture all the heterogeneity of the subsurface
- Measurement errors: due to a variety of often unavoidable issues in the field