  We extract the statistical uncertainties for the pion-nucleon ($\pi N$) low
energy constants (LECs) up to fourth order $\mathcal{O}(Q^4)$ in the chiral
expansion of the nuclear effective Lagrangian. The LECs are optimized with
respect to experimental scattering data. For comparison, we also present an
uncertainty quantification that is based solely on \pin{} scattering phase
shifts. Statistical errors on the LECs are critical in order to estimate the
subsequent uncertainties in \textit{ab initio} modeling of light and medium
mass nuclei which exploit chiral effective field theory. As an example of the
this, we present the first complete predictions with uncertainty quantification
of peripheral phase shifts of elastic proton-neutron scattering.
