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**The Gaussian hare and the Laplacian tortoise: computability of squared-error versus absolute-error estimators. With comments by Ronald A. Thisted and M. R. Osborne and a rejoinder by the authors.**
*(English)*
Zbl 0955.62608

Summary: Since the time of Gauss, it has been generally accepted that \(l_2\)-methods of combining observations by minimizing sums of squared errors have significant computational advantages over earlier \(l_1\)-methods based on minimization of absolute errors advocated by Boscovich, Laplace and others. However, \(l_1\)-methods are known to have significant robustness advantages over \(l_2\)-methods in many applications, and related quantile regression methods provide a useful, complementary approach to classical least-squares estimation of statistical models. Combining recent advances in interior point methods for solving linear programs with a new statistical preprocessing approach for \(l_1\)-type problems, we obtain a 10- to 100-fold improvement in computational speeds over current (simplex-based) \(l_1\)-algorithms in large problems, demonstrating that \(l_1\)-methods can be made competitive with \(l_2\)-methods in terms of computational speed throughout the entire range of problem sizes. Formal complexity results suggest that \(l_1\)-regression can be made faster than least-squares regression for \(n\) sufficiently large and \(p\) modest.

### MSC:

62J05 | Linear regression; mixed models |

### Software:

Algorithm 478
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\textit{S. Portnoy} and \textit{R. Koenker}, Stat. Sci. 12, No. 4, 279--300 (1997; Zbl 0955.62608)

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### References:

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