7. ORFscore
The ORFscore calculates the preference of RPFs to accumulate in the first frame of coding sequences.7 To compute the ORFscore RPFs are counted in each frame (in-frame,+1 frame,+2 frame). Next the distribution of RPFs is compared to an equally sized uniform distribution using a modified chi-squared statistic. Only RPFs with fragment lengths corresponding to the most abundant, in-frame RPFs found in canonical protein coding transcripts, are used.