# LIBS Info: Understanding: Why are there 2 measures of LIBS performance used on this site - Detection Limit and RMSE?

# Why are there 2 measures of LIBS performance used on this site - Detection Limit and RMSE?

The two measures attempt to answer different questions that are often asked about LIBS performance on a particular element.

Detection Limits are a measure of what the

**best**performance of LIBS on a particular element in a given matrix might be.

Root Mean Square Error (RMSE) is given by:

$$ \begin{aligned} RMSE = \sqrt{ \frac {\sum_{i=1}^n (concentration_{reference} - concentration_{measured})^2}{n}} \end{aligned} $$

It is provided as a measure of the

**routine or expected**performance of LIBS for an element on a given matrix.

This is particularly important for Chemometric or Calibration Free methods, but is also a useful measure for standard univariate calibrations.