We often read in NGS papers a descriptive value, called "N50", which seems to provide a standard measure of assembly connectivity. Could someone please explain, in details, the meaning of "N50" and how to compute this value?
Of course, N50, being a single number and an internal measure (using only information from the assembly itself, no external reference), is not very informative. I'm using a graphical display of the assemblies - still an internal measure (although you can also use e.g. EST data to use it as an external control). Some examples here.