Best way (mathematically/scientifically proven) to arrange spawners in Minecraft?

I ran some tests to try to get you closer to an answer. I built an area, 25 x 25 with a drop so zombies would spawn, fall, and be killed. I filled a horizontal plane with spawners all at the same distance from each other. I put the game mode on easy for 1 minute exactly. Then checked the drop count of rotten flesh. I ran the test multiple times to verify similar results each time. I then changed the distance of the spawners and ran the test again. I did this with spawner gap distance of 1, 2, 3, and 4.

I placed spawners 3rd down from the ceiling to allow spawns at level above spawners. I placed on block top of each spawner to prevent mobs from spawning on top of spawner.

Here is a picture of the different distances on spawners:

The averages of the results:

Gap of 1 = 566
Gap of 2 = 360
Gap of 3 = 258
Gap of 4 = 162

More spawners is more important then more spawn area.

Edit: I kept playing with this. I made the same test with a gap of one but I put a second spawner under each spawner.

The one minute test yielded an average of 936. A large increase.

I was directly in the middle, right under the spawners, in order to activate as many as possible when the tests were run.

Here is a picture of the last build raining zombies (I am using freecam to get this):