Originally…

This query was initially designed to mimic the random cloning of fragments of a given size.

and if needed...

If you need sampling without replacement, please let us know and we will add this option to the query.

Description of the genome query for

Select Random Loci

The user is prompted to enter the number of clusters and the size of each cluster.

Since sampling is with replacement, the number of loci returned may be less than <number> * <size>, since the same locus may randomly be chosen more than once, and/or the clusters of loci may overlap one another.

The random number generator used here is ran3( ), modified from Press et al. (1992) Numerical Recipes in C.

Example:

If one selects Aquifex aeolicus from the genomic pop-up menu, and enters 50 clusters of 50 genes, one might get 1275 out of A. aeolicus's 1553 ORFs listed, depending on chance. As discussed above, this number is significantly less than 50x50=2500 since sampling is with replacement.