So you can compare statistics on West Nile Virus infections per head of population in Louisiana with AIDS in Maryland, for example. Should you see any point in so doing.

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Note added at 56 mins (2008-11-28 11:15:55 GMT)
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La RECHERCHE CROISEE permet d'entrer PLUSIEURS CRITERES DE RECHERCHE à la fois
http://pharmtox.free.fr/liens/pdts_chim.htm

LawCrawler RECHERCHE CROISEE PAR SUJET ET ZONE GEOGRAPHIQUE.
http://www.geoscopies.net/sources/INTERNET/sit33dro.php

est possible de faire une RECHERCHE CROISEE SELON 4 CRITERES pour .... L' appel des liens est-il explicité (ou limité) à l'accès à un glossaire ? ...
nte-serveur.univ-lyon1.fr/tribollet/RegionR-A/Rubriques/criteres.html

Enfin, pour lire ces pages plus tranquillement, il existe un glossaire ..... par liste) ou d’effectuer une RECHERCHE PAR CRITERES (RECHERCHE CROISEE). ...
www.imageson.org/document654.html


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Note added at 58 mins (2008-11-28 11:17:30 GMT)
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Or more to the point, WNV infections in Louisiana in August with WNV infections in Minnesota in July. Or something meteorological like that.

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Note added at 3 hrs (2008-11-28 13:57:34 GMT)
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Discussion:
For me, a CROSS SEARCH would be where the Louisiana Disease Database, when interrogated about WNV infections in July, can connect to the Minnesota Disease Database for data for the same period.

True, a comparative search (in a national database) would involve multiple criteria, e.g. WNV INFECTION in JULY in LOUISIANA and MINNESOTA (1 disease, 1 month, 2 states)

But a REAL multicriteria search would involve more, e.g. WNV INFECTION in JULY in LOUISIANA and in AUGUST in MINNESOTA, i.e. a variation in criteria (1 disease, 2 states, and two different months, a different month for each state), or
WNV INFECTION in JULY in LOUISIANA and cases of MALARIA in AUGUST in MINNESOTA, i.e. a variation in criteria (2 diseases in 2 different months in 2 different states), etc. This also provides data for comparative purposes, but the data is not comparably comparable!