[REN plot for a graphic expression method of clinical laboratory data statistics].

Laboratory data have been processed statistically on an assumption that they formed a normal distribution curve by themselves or after their transformation. The data of clinical medicine, however, frequently form distributions different from the normal one and thus they are not exactly represented by simple statistics such as mean and standard deviation. We used non-parametric percentiles(pct) as parameters for an improved expression of data distributions. The parameters used in this method are as follows: mean, 50 pct as median, 25 and 75pct as a concentration indicator, 5 and 95pct as a 90 percent central range, 2.5 and 97.5pct as a 95 percent central range, and minimum and maximum data as a distribution range. These indicators were presented on a new form of box-and-whisker plot. This expression was named as REN plot. Our method was compared to the other statistical expression methods using the data of control surveys of Factor IX activity of normal plasmas and prothrombin time of abnormal standard plasmas as well as APTT of abnormal plasma measured for intra-laboratory quality control. It was found that any form of data distribution, normal or abnormal, was precisely expressed in detail and the gradient of data densities were visually plotted by our method. Also neither the median, central range nor distribution range was influenced by extreme values. It was concluded that REN plot was useful expression for the statistical analysis of clinical laboratory data.