When you grill goods, you hope for even browning and even cooking, but different rack positions don't always produce the same results. This parchment test from Cook's Illustrated will help you find the best zone in your broiler.
It's especially useful if you have an electric grill, whose rods could create hot spots and, thus, uneven cooking.
To do the test, grill parchment at each position and look for the one that comes out most like the one in the middle in the photo above.
The Parchment Test: Finding the Broiler Sweet Spot [Cook's Illustrated]