Shin-ichi Matsuda

Choice of Multiple Representative Signatures for On-line Signature Verification Using a Clustering Procedure

The task of signature verification is to judge whether the writer of a signature is truly the declared person or not, by referring to a previously provided signature database. The verification is completed when the observed dissimilarity between the questioned signature and a set of signatures, which were previously written by the declared person and included in the database, is less than a given threshold. This paper proved, through a verification experiment using a signature database supplied by CADIX Co. Ltd., that the use of multiple representatives, which represent respective clusters constructed by a clustering procedure, is effective. According to the experiment, the resulting error rate decreased from about 6% to about 1% on average by increasing the number of representatives from one to three.

Closed testing procedures for all pairwise comparisons in a randomized block design

ABSTRACT We consider multiple comparison test procedures among treatment effects in a randomized block design. We propose closed testing procedures based on maximum values of some two-sample t test statistics and based on F test statistics. It is shown that the proposed procedures are more powerful than single-step procedures and the REGW (Ryan/Einot–Gabriel/Welsch)-type tests. Next, we consider the randomized block design under simple ordered restrictions of treatment effects. We propose closed testing procedures based on maximum values of two-sample one-sided t test statistics and based on Batholomew’s statistics for all pairwise comparisons of treatment effects. Although single-step multiple comparison procedures are utilized in general, the power of these procedures is low for a large number of groups. The closed testing procedures stated in the present article are more powerful than the single-step procedures. Simulation studies are performed under the null hypothesis and some alternative hypotheses. In this studies, the proposed procedures show a good performance.