About two PPLs
stolcke at speech.sri.com
Fri Feb 28 21:38:08 PST 2003
In message <002101c2dfb4$8801ec90$6314ce80 at speechwork>you wrote:
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> I have installed srilm successfully, thanks a lot! Now I have a =
> small question about PPL output:
> when I run "ngram" to count PPL of a testing text, there are two =
> ppls output: ppl and ppl1, what's the difference of them?=20
> =A3=A8I can't find this from the documents).
ppl is the perplexity normalized over all input tokens,
ppl1 is omits end-of-sentence tokens from the denominator.
ppl1 is more meaningful for comparing texts that differ in their
BTW, this will be documented in the man page for the next release.
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