Table 2.

Results: Internal Anal Sphincter Measurements

	Young Group ≤30 years (n=32)	Old Group ≥50 years (n=32)	P Value	Effect-size Cohen's d
Inner	7.1±1.3	8.5±1.8	0.001	0.89
diameter
(mm)
Outer	16±2.1	20.3±3.3	0.001	1.55
diameter
(mm)
Mean	4.5±0.7	5.9±1	<0.001	1.62
thickness
(mm)

Data are means±standard deviations unless otherwise indicated.

These results are averages from two blinded investigators taken from consecutive axial magnetic resonance imaging (MRI) slices (3−5). Student's t-test was performed to test for statistical significance as well as Cohen's d for effect size. Note the larger inner and outer diameter as well as larger mean thickness in the elderly.