ExomeDepth negative BF (bayesian factor) values meaning

Question

[John]

Hello, I just analyzed a few WES samples and I found negative BF value at some positions. How can I this interpreting? Example:

BF= -75
READS_EXPECTED= 500
READ_OBSERVED= 750
RATIO= 1.44

And status is "deletion".

Thank you very much for help with interpretation of this result. I would expecting this result as duplication.

Best,

John.

[German.M.Demidov]

If it is a real CNV it should be a duplication. Something wrong happened with the definition of deletion here xD

Answer 1

[Jorge Amigo]

Since the Bayes Factor is "the log10 of the likelihood ratio of data for the CNV call divided by the null (normal copy number)" as stated here, negative values just mean that the likelihood ratios are between 0 and 1, therefore the confidence levels of those CNV calls are extremely low.