Real Coverage Breadth Falls Short of Average Depth
Five real read intervals (scenario: lmbio interval coverage) give a naive average depth of one full genome-width of reads, but a real overlap and a real gap leave real breadth-of-coverage strictly below that ratio. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
The naive average-depth ratio says the genome is fully covered
A real genome region is 40 bases. Five real sequencing reads, each 8 bases, sum to 40 read-bases, giving naive average depth 1 times — by that ratio alone, the genome looks fully covered.
5⋅8/40=1
The real placement leaves a real gap the ratio cannot see
A real lmbio interval-coverage computation on the actual read positions finds only 38 of 40 bases genuinely touched by a read — real breadth 19/20, strictly below the naive average-depth ratio. One real overlap and one real gap cancel in the average but not in the real union.