If you are drawing a venn diagram with only two circles of equal radius overlapping, the distance between the centers is a direct (but thorny) function of the common proportion you wish to display. You can come very close with the following formula: y = 3.5179*x^4 - 8.1729*x^3 + 6.8236*x^2 - 4.1096*x + 1.9692 where y is the distance between the centers in terms of proportion of the radius and x is the desired proportion in common. Dr. Terry Froman Miami-Dade Public Schools [EMAIL PROTECTED] ================================================================= Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =================================================================