FXIII activity, levels, and specific activity (SA) within the normal study population. The Kolmogorov-Smirnov Goodness of Fit Test was used to test the hypothesis that the values obtained for FXIII levels, activity, and SA match a normal distribution. The value of the Kolmogorov-Smirnov test is based on the largest absolute difference between the observed and the theoretical cumulative distributions. The two-tailed probability value was used to decide whether the null hypothesis should be rejected. This is the probability of obtaining results as extreme as the ones observed, in either direction, when the null hypothesis is true. Because the two-tailed P values obtained are much higher than .05, the null hypothesis is not rejected, and hence the variation observed in FXIII levels, activity, and SA fits a normal distribution. For (A) to (C) the normal distribution curve is also plotted for comparison. (A) This histogram illustrates the variation seen in plasma FXIII levels in 73 unrelated individuals comprising 22 normal men, 37 normal women, and 14 RM women. (B) The distribution of plasma FXIII activity in 72 unrelated individuals comprising 23 normal men, 35 normal women, and 14 from RM group. (C) FXIII SA was defined as FXIII activity per unit FXIII level, this being 1.0 (ie, 100% activity/100% level) for the standard normal plasma. SA of plasma FXIII in 71 unrelated individuals (comprising 22 normal men, 35 normal women, and 14 RM women) mean age, 30.2 years, ± 5.5 standard deviation; age range, 18 to 48. (D) A normal probability plot was used to determine whether FXIII SA is normally distributed. The cumulative proportion for a single numeric variable is plotted against the cumulative proportion expected if the sample were from a normal distribution. Because the points all cluster around a straight line, this suggests that FXIII SA has a normal distribution within the population studied. SD, standard deviation; N, numbers studied; KS, Kolmogorov-Smirnov Test; P, two-tailed probability value.