Terry,
The thing one has to remember about search engines is that they are
temperamental beasts. AltaVista in particular is prone to throwing
tantrums and sometimes won't come out to play at all:-)
On the default search issue, AV changed a few months ago and tries
first of all to identify and match phrases in your search strategy.
If you have only two or three words and there are a substantial
number of hits for those as a whole phrase, it stops there and does
not bother to do an "or" search. It will now even identify multiple
phrases in your search. For example:
low fat food cholesterol lowering
is treated as:
"low fat food" "cholesterol lowering"
The order of the words does sometimes matter. I tried swapping your
terms round (union monetary) and got what one would expect for an OR
search (477,510)although that is substantially lower than the OR
search in the Advanced Search.
Adding in an extra term (monetary union UK)threw a spanner in its
phrase identification works and gave 1,109,290 hits!
> The result for a real OR search,
> obtained by using OR (which has to be in upper case) on the
> advanced search screen is 4,223,763.
When I tried that on the advanced search screen I got a mere(?)
2,767,825, considerably less than yours. This could either be the
infamous timing out "feature" of AV, or the rumour that the full
database is not always available for searching may be true. I think
that as I did the search late afternoon UK time it did in fact time
out.
That is borne out by my Simple Search on union monetary giving far
fewer hits. In Simple Search, some of the time allocated to the
search is taken up by the relevance ranking: in the Advanced Search
relevance ranking is not used and so AV has more time to spend on
searching the database.
> Curioser still, if you type in
>
> monetary union
>
> on the advanced search screen (where the default is again meant
> to be OR) then the answer is 480580.
I suspect that this is the phrase matching at work again but it is
interesting that it gives more than the phrase search on the simple
search screen. Absence of relevance ranking at work again and
therefore more time available for the actual search?
> The basic search uses + to ensure a word
> is present (equivalent conceptually to AND). However a search for
>
> +monetary +union
>
> yields 85872
>
> whereas searching in advanced mode for
>
> monetary AND union
>
> gives 919290
Now this is where we differ - the plus search gave me 84380 and the
AND search far less with 6052 (I suspect timing out here).
> What is one to think? Worse still what is one to tell the
> students?
That some of the search engines (and AltaVista in particular) are
erratic and not to be trusted? The trouble is that when one does
eventually work out what is going on, the search engine bods change
the rules and we have to start all over again :-((
Karen
--
Karen Blakeman, RBA Information Services
Tel:0118 947 2256, Fax:0870 056 8547
E-Mail:[log in to unmask]
http://www.rba.co.uk/
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