Fig. 2

College of American Pathologists (CAP) 2018 Educational Exercise: analyses of the reported fetal fraction results. (a) Each of the 56 participant’s fetal fraction estimates is expressed as a ratio to the intended response, similar to a multiple of the median (MoM). The open circles are the median fetal fraction expressed in MoM while the bars indicate the range of values. Results are sorted from low to high median value. Filled circles indicate participants whose summary results are below 0.8 or above 1.2 MoM. (b) Intended fetal fraction on the horizontal axis and the reported fetal fraction for distribution A. The large “X” symbols are drawn at the mean reported fetal fraction for all challenges having that intended fetal fraction. In theory, these should follow the line of identity (Y = X, dashed line). (c) Same as (b) except that it displays results from distribution B. In (c) the bold open squares and filled diamonds at the intended fetal fraction of 11% are from two separate lots and are discussed in “Results.” NIPT noninvasive prenatal testing.