Paul Jaccard

Paul Jaccard , born the November 18th 1868 with Holy-Cross and dead the May 9th 1944 with Zurich, is a professor Suisse of Botanique, specialist in vegetable Physiologie.

Biography

First of all teacher in the village of Chexbres in 1887, it follows studies of natural science as of 1889 to the Université of Lausanne, then with that of Zurich where it obtains his doctorate in 1894.

He is then named privatdocent at the university of Lausanne between 1894 and 1903 before leaving for the federal polytechnic school Zurich where he teaches general botany and the physiology of the plants.

During its career, it accomplishes several study trips in Egypt, Sweden and to the Turkestan where it is interested particularly in the growth of the trees.

Contributions in mathematics

Paul Jaccard is at the origin of two measurements used in statistics, the index (or coefficient) of Jaccard, and distance it from Jaccard.

The index describes the relationship between the size of the intersection of the two units and the size of the union of two units. More formally, by considering two units has and b:

$J (has, B) = |With \ course B|/|With \ cup B|$

The distance has as a definition: $J_ {\ delta} (has, B) = 1 - J (has, B) = {{ |With \ cup B| - |With \ course B| } \ over |With \ cup B| }$ .

Within the framework of biology, the index of Jaccard makes it possible to estimate the diversity of the species between two samples. The distance allows as for it the reverse, namely to measure the defects of similarity between the samples.

External bonds and references

Card of the Swiss historical Dictionary

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