Estimation of transcript and cDNA insert lengths through EST to reference transcript alignments. Using EST-to-transcript alignments to estimate cDNA insert and originating transcript length distributions for EST libraries. 5'-EST alignment positions are used to determine the size of cDNA inserts. Reference transcripts matched by either 5'- or 3'- ESTs are used to estimate the sampled transcript lengths. Black lines represent polyadenylated mRNA transcripts, and 5'-ESTs and 3'-ESTs are represented in blue and red, respectively.