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. Author manuscript; available in PMC: 2014 Aug 1.
Published in final edited form as: Biol Psychiatry. 2013 Apr 25;74(3):204–211. doi: 10.1016/j.biopsych.2013.03.006

Figure 3.

Figure 3

(A) The frequencies of total trophoblast inclusions (TIs) in the control placentas was very closely fit by a single Poisson distribution with the sample mean of .4 TIs/case (χ2 = .86, p = .65, 2 degrees of freedom with counts at and above two combined together). (B) The frequencies of TIs in the MARBLES (Markers of Autism Risk in Babies-Learning Early Signs) placentas did not fit a single Poisson distribution when using the sample mean of 2.03 TIs/case (χ2 = 71.4, p < .001, 5 degrees of freedom with counts at and above five combined together). (C) When a two-component mixture of Poisson distributions was fit (with mixing weights of .82 and .18 and means of .99 and 6.88 TIs/case for the two component distributions, respectively) a much closer fit was achieved (χ2 = 4.07, p = .25, 3 degrees of freedom with counts at and above five combined together). All estimates were maximum likelihood.