### Navigation

- index
- modules |
- next |
- previous |
- statsmodels v0.2.0 documentation »
- Robust Linear Models »
- scikits.statsmodels.robust.norms.RobustNorm »

# scikits.statsmodels.robust.norms.RobustNorm.psi_deriv

`RobustNorm.``psi_deriv`(z)

  Abstract method:

  psi_derive = psi’

### Navigation

- index
- modules |
- next |
- previous |
- statsmodels v0.2.0 documentation »
- Robust Linear Models »
- scikits.statsmodels.robust.norms.RobustNorm »