BODY FAT via calipers

I decided to try an interesting expirement this week.

I first took my body fat skin fold measurements; then I took my body part circumference measurements (neck, chest, biceps, etc.); then I took my skin fold measurements a second time.

I always take skinfold measurements at 3 sites: Pectoral, stomach and thigh; at each location I take 5 measurements -- I then discard the low and high measurements. The web-calculator I use automatically averages the middle three numbers.

The numbers from first round:

P: 18, 19, 18, 19, 17 (19 and 17 eliminated);
S: 53, 48, 48, 50, 41 (53 and 41 eliminated); and
T: 16, 16, 15, 16, 14 (16 and 14 eliminated).

The second round numbers:

P: 16, 17, 17, 17, 16 (16 and 17 eliminated);
S: 53, 47, 51, 48, 46 (53 and 46 eliminated); and
T: 13, 15, 15, 16, 15 (13 and 16 eliminated).

first round: 24.726%
second round: 24.125%

So a difference of 0.6% -- a significant (but not mindblowing) difference. So the differences I've seen recently in the spreadsheet seems to be a "wizard not the wand" issue. It's me not the caliper.