Blocked 3×2 cross-validated t-test for comparing supervised classification learning algorithms.

In the research of machine learning algorithms for classification tasks, the comparison of the performances of algorithms is extremely important, and a statistical test of significance for generalization error is often used to perform it in the machine learning literature. In view of the randomness of partitions in cross-validation, a new blocked 3×2 cross-validation is proposed to estimate generalization error in this letter. We then conduct an analysis of variance of the blocked 3×2 cross-validated estimator. A relatively conservative variance estimator that considers the correlation between any two two-fold cross-validations, and was previously neglected in 5×2 cross-validated t and F-tests is put forward. A corresponding test using this variance estimator is presented to compare the performances of algorithms. Simulated results show that the performance of our test is comparable with that of 5×2 cross-validated tests but with less computation complexity.

ISSR analysis of genetic diversity of Coptis deltoidea / 中国中药杂志

<p><b>OBJECTIVE</b>To study the genetic diversity of Coptis deltoidea.</p><p><b>METHOD</b>The genetic diversity of 90 individuals from 8 populations was analyzed by ISSR.</p><p><b>RESULT</b>Twelve primers were selected to produce highly reproducible ISSR bands. Among 128 amplified bands, 94 showed polymorphism, the percentage of polymorphic bands reached 73.44%. Nei's gene diversity index (H) was 0.1925, Shannon's information index (I) was 0.3028, Gst was 0.7212. The genetic distance coefficient and similarity were 0.0858-0.2314 and 0.8046-0.9425, respectively.</p><p><b>CONCLUSION</b>C. deltoidea held a high genetic diversity and the majority of genetic variation occurs among populations. By cluster analysis, the geographical distribution is very obvious. The ISSR marker can be used for the analysis of genetic diversity and genetic variation of C. deltoidea.</p>

ISSR Analysis for genetic diversity of Coptis chinensis / 中草药

Objective To discuss the genetic diversity of Coptis chinensis.Methods The genetic diversity of 78 individuals from seven populations was analyzed by inter-simple sequence repeat(ISSR).Results Twelve primers were selected to produce highly reproducible ISSR bands.Among 106 amplified bands,72 showed polymorphism,the percentage of polymorphic bands reached to 67.92%.Nei's gene diversity index(H)was 0.180 3,Shannon information index(I)was 0.283 2,Gst was 0.681 5.The genetic distance coefficient and genetic similarity were 0.089 4—0.184 6 and 0.832 1—0.912 7,respectively.ConclusionC.chinensis holds high genetic diversity and the majority of genetic variation occurs among the populations.By cluster analysis,the geographical distribution is very obvious.The ISSR marker could be used for the analysis of the genetic diversity and genetic variation of C.chinensis.