title: Transformation in the PC-aided biochemical data analysis.
abstract: Data transformations enable expression of original data in a new scale, more suitable for data analysis. In computer-aided interactive analysis of biochemical and clinical data an exploratory data analysis often finds that the sample distribution is systematically skewed or does not accept a sample homogeneity. Under such circumstances the original data should be transformed. The power transformation and the Box-Cox transformation improve sample symmetry and also stabilize variance. Both the Hines-Hines selection graph and the plot of logarithm of a maximum likelihood function allow selection of an optimum transformation parameter. The proposed procedure of data transformation in univariate data analysis is illustrated on a determination of 17-hydroxypregnenolone in umbilical blood of a population of newborns. Lower levels of free 5-ene steroids in umbilical blood and elevated levels of 5-ene steroid sulfates indicate a congenital sex-specific placental sulfatase insufficiency. After examination of statistical assumptions by diagnostic plots of an exploratory data analysis the best estimate of a mean value of 17-hydroxypregnenolone is derived.
authors.affiliation: Department of Analytical Chemistry, Faculty of Chemical Technology, University Pardubice, Czech Republic. milan.meloun@upce.cz
authors.forename: M
authors.initials: M
authors.lastname: Meloun
authors.forename: M
authors.initials: M
authors.lastname: Hill
authors.forename: J
authors.initials: J
authors.lastname: Militký
authors.forename: K
authors.initials: K
authors.lastname: Kupka
mesh_terms: D006907:17-alpha-Hydroxypregnenolone / Q000097:blood; D001669:Biochemical Phenomena; D001671:Biochemistry; D005312:Fetal Blood; D006801:Humans; D007231:Infant, Newborn; D008838:Microcomputers; D013223:Statistics as Topic
chemical_list: D006907:17-alpha-Hydroxypregnenolone