7 Dec 1997 22:10:00 -0500

Related articles |
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Q: least-square fit for performance model chunghsu@paul.rutgers.edu (Chung-Hsing Hsu) (1997-12-05) |

Re: Q: least-square fit for performance model henry@zoo.toronto.edu (Henry Spencer) (1997-12-07) |

From: | Henry Spencer <henry@zoo.toronto.edu> |

Newsgroups: | comp.benchmarks,comp.compilers,comp.arch |

Date: | 7 Dec 1997 22:10:00 -0500 |

Organization: | SP Systems, Toronto |

References: | 97-12-039 |

Keywords: | benchmarks, performance |

Chung-Hsing Hsu <chunghsu@paul.rutgers.edu> wrote:

*>Is there any literature discussing how suitable it is to use*

*>least-square fitting to get the performance model of a set of*

*>benchmarks? ...*

A small comment on statistical methods: there are good reasons *not*

to use least-squares fitting if the number of data points is small and

the data is noisy. Least-squares fitting is not robust; even with

large numbers of points, it can give badly distorted answers if most

of the data follows an obvious pattern but there are a few "outlier"

points far outside the pattern. With small numbers of points the

answers can be almost meaningless.

Professional statistical advice is important for such attempts to

extract meaning from very limited data. You should seek it *before*

you start work, not after you've gathered your data -- it may well

influence how much data you gather, and how you gather it. Such

advice is best sought in a Statistics or Applied Math department, not

in a book or on Usenet or the Web, and you'll probably have to pay for

it. It's worth it.

--

| Henry Spencer

| henry@zoo.toronto.edu

--

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