Open AccessA Comparison of One‐ and Two‐Sided Tests for Judging Significant Differences in Quantitative Data Obtained in Toxicological Bioassay of Laboratory Animals
Author(s) -
Kobayashi Katsumi
Publication year - 1997
Publication title -
journal of occupational health
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.664
H-Index - 59
ISSN - 1348-9585
DOI - 10.1539/joh.39.29
Subject(s) - statistics , mathematics , test (biology) , toxicology , bioassay , statistical analysis , medicine , biology , paleontology , genetics
A Comparison of One‐ and Two‐Sided Tests for Judging Significant Differences in Quantitative Data Obtained in Toxicological Bioassay of Laboratory Animals. Katsumi K obayashi . Biosafety Research Center, Foods, Drugs and Pesticides —Since there are many ambiguous statements concerning the selection of one‐ or two‐sided tests in the statistical analysis of toxicological data, I examined the rate of appearance of significant differences in the data showing a trend in either a fixed direction or a mixed sided direction compared with the control and the number of significant differences to these two tests by t and Dunnett's tests in a long‐term chronic/carcinogenicity study conducted at the An‐Pyo Center, in addition to referring to the most widely used statistical analyses by mean of the one‐or two‐sided test in the literature. The results were as follows; (1) Almost all quantitative data (578 out of 700 cases) showed a fixed trend with statistically significant differences (p<0.05) compared with the control value. (2) The number of significant differences obtained with the one‐sided test was greater than with the two‐sided test in either analysis of the t or Dunnett's test; that is, the percentages of the significant differences in the two‐sided test were 85 and 86% of those in the one‐sided test by means of t and Dunnett's test, respectively. (3) The frequency of use of the one‐sided tests was very low in both Japanese and international publications. Consequently, the one‐sided test may be recommended for statistical analyses of toxicological bioassay data that generally show a fixed trend as compared with the control values, since more rigid evaluation of the data of the chemical effects on the living body and the environment is necessary.