[SRILM User List] SRILM parameters

Andreas Stolcke stolcke at icsi.berkeley.edu
Mon May 23 11:02:11 PDT 2011

Casey Kennington wrote:
> Andreas,
> I've emailed you before and you were quick to response, so I am hoping 
> I will get another quick response! This time it's about how SRILM 
> calculates perplexity. I know the FAQ says:
> ppl = 10^(-logprob / (words - OOVs + sentences))
> But what exactly is your logprob? Is that a single logprob of the 
> entire eval corpus? Is it an average logprob of all sentences?

logprob is what ngram -ppl prints out after "logprob=" , i.e., the sum 
of the log probabilities over the entire test set.


PS. Please direct future questions to the mailing list

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