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# scikits.statsmodels.robust.norms.TukeyBiweight

class `scikits.statsmodels.robust.norms.``TukeyBiweight`(c=4.6849999999999996)

  Tukey’s biweight function for M-estimation.

  Parameters: | c : float, optional The tuning constant for Tukey’s Biweight. The default value is c = 4.685.

  Notes

  Tukey’s biweight is sometime’s called bisquare.

  Methods

  `psi`(z) | The psi function for Tukey’s biweight estimator
  `psi_deriv`(z) | The derivative of Tukey’s biweight psi function
  `rho`(z) | The robust criterion function for Tukey’s biweight estimator
  `weights`(z) | Tukey’s biweight weighting function for the IRLS algorithm

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