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Asymptotic distribution of the distance-based classifier under a strongly spiked eigenvalue model (Bayes Inference and Its Related Topics)

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(1)1. 数理解析研究所講究録 第2047巻 2017年 1-9. Asymptotic. distribution of the distance‐Uased. classifier under. a. strongly spiked eigenvalue model. 東京理科大学. 情報科学科. 晶 (Aki Ishii). 石井. Department of Information Sciences Tokyo University of Science. Abstract: We consider two‐class classification for We consider the distance‐based classifier. (2014).. We. provide an asymptotic strongly spiked eigenvalue model.. high‐dimensional data. given by Aoshima and Yata. distribution of the classifier under. a. Key words and phrases: Asymptotic distribution, Distance‐based clas‐ sifier, HDLSS, Large p small n. 1. Introduction. Nowadays, you can see many types of high‐dimensional data such as genetic microar‐ rays, medical imaging, text recognition, finance, chemometrics, and so on. A common feature of high‐dimensional data is that the data dimension is extremely high, however, the sample size is relatively low. We call such data “HDLSS” or “large p small n data, where p is the data dimension and n is the sample size. In this pepar, we consider two‐class classification in HDLSS context. We aim to give an asymptotic distribution of the distance‐Uased classifier under a strongly spiked eigenvalue model that was proposed by Aoshima and Yata (2017). Suppose we have two classes $\pi$_{l}, i=1 2, and define independent p\times n_{i} data matrices, X_{i}= [x_{i1}, x_{in_{i}}], i=1 2, from $\pi$_{i}, i=1 2, where x_{ij}, j=1, n_{l} are independent and identically distributed (i.i. \mathrm{d}. ) as a p‐dimensional distribution with a mean vector $\mu$_{i} and covariance matrix $\Sigma$_{i} (\geq O) We assume n_{i}\geq 3, i=1 2. The eigen‐decomposition of $\Sigma$_{i} is given by ”. ,. ,. ,. ,. ,. .. ,. $\Sigma$_{i}=H_{i}$\Lambda$_{i}H_{i}^{T}=\displaystyle\sum_{\mathcal{S}=1}^{p}$\lambda$_{s(i)}h_{s(i)}h_{s(i)}^{T}, diag ($\lambda$_{1(i)}, $\lambda$_{p(i)}) having $\lambda$_{1(i)} \geq\cdots\geq$\lambda$_{p(i)}(\geq 0) and H_{i}=[h_{1(i)}, h_{p(i)}] orthogonal matrix of the corresponding eigenvectors. Let X_{i} [$\mu$_{i}, $\mu$_{l}] for i 1 is a data from a distribu‐ matrix )2. Then, Z_{i} p\times n_{i} sphered H_{i}\mathrm{A}_{\dot{l} ^{1/2}Z_{i} tion with the zero mean and identity covariance matrix. Let Z_{i}= [z_{1(\dot{ $\iota$})}, z_{p(i)}]^{T} and where \mathrm{A}_{i}= is. an. =. -. =. z_{j(\mathrm{i})}=. (z_{j1(i)}, z_{jn_{i}(i)})^{T},. p , for i=1 , 2. Note that. j=1,. E(z_{jk(i)}z_{j'k(i)})=0(j\neq j'). identity matrix. Also, note \mathrm{V}\mathrm{a}\mathrm{r}(z_{j(i)})=I_{n_{i} that if X_{i} is Gaussian, are i.i. \mathrm{d} as the standard normal distribution, N(0,1) We z_{jk(i)}\mathrm{s} assume that the fourth moments of each variable in Z_{i} are uniformly bounded for i=1 2. and. ,. where. I_{n_{i}}. denotes the n_{i} ‐dimensional .. .. ,. Let. z_{oj(i)}=z_{j(\dot{ $\iota$})}-. (\overline{z}_{j(i)}, \overline{z}_{j(i)})^{T},. j=1,. p ; i=1 ,. 2, where. \displaystyle \overline{z}_{j(\mathrm{i})}=n_{i}^{-1}\sum_{k=1}^{n_{i} z_{jk(i)}..

(2) 2. We. assume. Euclidean. =. x_{0} and. an. observation vector of. x_{ij}\mathrm{s}. are. independent.. 1,. =. 2, where ||. ||. denotes the. an. an. belonging to $\pi$_{i} (i = 1,2) We $\Sigma$_{i} by \displaystyle \overline{x}_{in_{i} =\sum_{j=1}^{n_{i} x_{ $\iota$ j}/n_{\dot{l} and typical classification rule is that one. individual. .. We estimate $\mu$_{i} and. S_{ $\iota$ n_{\dot{l} }=\displaystyle \sum_{j=1}^{n_{i} (x_{ij}-\overline{x}_{in_{i} )(x_{\dot{ $\iota$}j}-\overline{x}_{in_{i} )^{T}/(n_{i}-1). classifies. 1 for i. norm.. Let x_{0} be assume. (\displaystyle \lim_{p\rightarrow\infty}||z_{o1(i)}|| \neq 0). that P. A. .. individual into $\pi$_{1} if. (x_{0}-\displaystyle \overline{x}_{1n_{1} )^{T}S_{1n1}^{-1}(x_{0}-\overline{x}_{1n_{1} )-\log\{\frac{\det(S_{2n_{2} )}{\det(S_{1n_{1} )}\} <(x_{0}-\overline{x}_{2n_{2} )^{T}S_{2n_{2} ^{-1}(x_{0}-\overline{x}_{2n_{2} ). (1.1). ,. and into $\pi$_{2} otherwise. However) the inverse matrix of S_{in_{i}} does not exist in the HDLSS context (p > n_{i}) When $\Sigma$_{1} $\Sigma$_{2} Bickel and Levina (2004) considered the inverse =. .. matrix defined. by only diagonal. ,. elements of the. pooled sample covariance matrix. Yata ridge‐type inverse covariance matrix derived by the noise reduction (NR) methodology. When $\Sigma$_{1} \neq $\Sigma$_{2} Dudoit et al. (2002) consid‐ ered using the inverse matrix defined by only diagonal elements of S_{in_{i}} Aoshima and Yata (2011,2015\mathrm{a}) considered substituting \{\mathrm{t}\mathrm{r}(S_{in_{i} )/p\}I_{p} for S_{in_{i}} by using the differ‐ and Aoshima. (2012). considered using. a. ,. .. of. geometric representation of HDLSS data from each $\pi$_{l} Aoshima and Yata quadratic classifiers in general and discussed asymptotic properties (2015b) and optimality of the classifies under high‐dimensional settings. They showed that the misclassification rates tend to zero as the dimension goes to infinity. On the other hand, ence. a. .. considered. Hall et al.. (2005, 2008), and Chan and Hall (2009) considered distance‐based classifiers. (2014) gave the misclassification rate adjusted classifier for multiclass,. Aoshima and Yata. high‐dimensional data whose misclassification rates under the following condition for eigenvalues:. \displaytle\frac{$\lambda$_{1(i)}^{2 \mathrm{}\ athrm{}($\Sigma$_{i}^2)\rightarow0 Recently, Aoshima model”’. as. and Yata. (2017). are no more. than. specified thresholds. (1.2). p\rightarrow\infty for i=1 , 2.. as. considered the. “strongly spiked eigenvalue (SSE). follows:. \displaystle\im\ athrm{i}\mathrm{}\mathrm{J}p\rightarow\infty\mathrm{f}\ rac{$\lambda$_{1(i)}^{2 \mathrm{t}\mathrm{}($\Sigma$_{i}^2)}\>0. for i=1. On the other hand, Aoshima and Yata (2017) eigenvalue (NSSE) model” In this paper,. we. Remark 1.1. For. a. called. or. (1.3). 2.. (1.2). the. consider the distance‐Uased classifier under. spiked model such. “non‐strongly spiked. one. of the SSE models.. as. $\lambda$_{s(i)}=a_{s(i)}p^{$\alpha$_{s(i)} (s=1, t_{I}\cdot). and. $\lambda$_{s(i)}=c_{s(i)} (s=t_{i}+1, \ldots,p). (1.4). with positive and fixed constants, a_{s(i)}\mathrm{s}, c_{s(\dot{l})}\mathrm{s} and $\alpha$_{s(i)}\mathrm{s} , and a positive and fixed integer t_{i} , note that (1.2) holds when $\alpha$_{1(i)} <1/2 for i=1 , 2. On the other hand, (1.3) holds for the spiked model in (1.4) with \geq 1/2 See Yata and Aoshima (2012) for the details of the spiked model.. $\alpha$_{1(i)}. ..

(3) 3. 2. Distance‐based classifier Aoshima and Yata matrix. I_{p}. instead of. (2014) considered a classification rule given by using the identity in (1.1) as follows: One classifies an individual into $\pi$_{1} if. S_{in_{i}}. (x_{0}-\displaystyle \frac{\overline{x}_{1n}1+\overline{x}_{2n2} {2})^{T}(\overline{x}_{2n_{2} -\overline{x}_{1n_{1} )-\frac{\mathrm{t}\mathrm{r}(S_{1n_{1} )}{2n_{1} +\frac{\mathrm{t}\mathrm{r}(S_{2n_{2} )}{2n_{2} <0. (2.1). and into $\pi$_{2} otherwise. Here, -\mathrm{t}\mathrm{r}(S_{1n1})/(2n_{1})+\mathrm{t}\mathrm{r}(S_{2n_{2}})/(2n_{2}) is a bias‐correction term. showed the asymptotic normality of the classifier and provide a sample size deter‐. They. mination. They. to control misclassification rates. so as. further. developed. Remark 2.1. Chan and Hall as. being. no more. than. a. prespecified value.. the classifier to multiclass classification.. follows: One classifies. an. (2009). considered. a. scale. adjusted distance‐based classifier. individual into $\pi$_{1} if. \displaystyle\sum_{j=1}^{n_{1} \frac{|x_{0}-x_{1j}|^{2} {n_{1} -\sum_{j=1}^{n_{2} \frac{|x_{0}-x_{2j}|^{2} {n_{2} -\sum_{i=1}^{n_{1} \sum_{j=1}^{n_{1} \frac{|x_{1i}-x_{1j}|^{2} {2n_{1}(n_{1}-1)} +\displaystyle \sum\sum^{n_{2} \frac{|x_{2i}-x_{2j}|^{2} {2n_{2}(n_{2}-1)}n_{2}<0. (2.2). i=1j=1. and into. $\pi$_{2}. otherwise. We note that the classifier given by (2.1) is equivalent to the is much simpler than (2.2).. one. given by (2.2), though the description of (2.1) We denote the. by e(1). or. of. misclassifying an individual e(2) respectively. Let $\Delta$=||$\mu$_{1}-$\mu$_{2}||^{2} and error. (into. from $\pi$_{1}. $\pi$_{2}. ). or. $\pi$_{2}. (into. $\pi$_{1}. ). ,. W(x_{0})= (x_{0}-\displaystyle \frac{\overline{x}_{1n_{1} +\overline{x}_{2n_{2} {2})^{T}(\overline{x}_{2n_{2} -\overline{x}_{1n_{1} )-\frac{\mathrm{t}\mathrm{r}(S_{1n_{1} )}{2n_{1} +\frac{\mathrm{t}\mathrm{r}(S_{2n_{2} )}{2n_{2} . Aoshima and Yata. (2014). considered asymptotic properties of W(x_{0}) under the. following. assumptions:. (A‐i). \displaystyle \frac{($\mu$_{1}-$\mu$_{2})^{T}$\Sigma$_{i}($\mu$_{1}-$\mu$_{2}) {$\Delta$^{2} \rightar ow 0. (A‐ii). \displayst le\frac{\max_{j-1,2}\mathrm{t}\mathrm{r}($\Sigma$_{j}^{2}){n_{i}$\Delta$^{2}\rightarow0. Then, they Theorem 2.1 as. gave the. as. as. p\rightarrow\infty for i=1 ,. 2;. p\rightarrow\infty either when n_{i} is fixed. or. n_{i}\rightarrow\infty for i=1 , 2.. asymptotic consistency:. (Aoshima. and. Yata, 2014). Assume (A‐i) and (A‐ii). It holds that. p\rightarrow\infty. \displaystyle \frac{W(x_{0})}{ $\Delta$}=\frac{(-1)^{i} {2}+o_{p}(1) for i=1. ,. 2.. Then,. the. when x_{0}\in$\pi$_{i}. classification rule given by (2.1) has that. e(1)\rightarrow 0. and. e(2)\rightarrow 0.. as. p\rightarrow\infty.

(4) 4. Remark 2.2. Under the condition that. \displaystyle \max_{j=1,2}\{\mathrm{t}\mathrm{r}($\Sigma$_{j}^{2})\}/$\Delta$^{2}\rightar ow 0. claim Theorem 2.1 either when n_{i} is fixed. Aoshima and Yata. (2014). general factor. model. assume a. or. n_{\dot{l}}\rightarrow\infty for. as. p\rightarrow\infty ,. one can. i=1 , 2.. ako showed the asymptotic follows:. normality. of. (2.1). They. as. x_{ij}=$\Gamma$_{i}w_{ij}+$\mu$_{i} for. j=1,. n_{i} ; i=1 ,. and w_{ij}, j=1, As for. i.i. \mathrm{d}. w_{ij}=(w_{i1j}, \ldots,w_{ir_{i}j})^{T}. ( \mathrm{A}‐iii). is a p\times r_{i} matrix for some r_{i}>0 such that $\Gamma$_{l}$\Gamma$_{i}^{T}=$\Sigma$_{i}, random vectors having E(w_{ij})=0 and \mathrm{V}\mathrm{a}\mathrm{r}(w_{ij})=I_{r_{i} .. 2, where $\Gamma$_{i} are. n_{i} ). ). .. i=1 ). 2,. that. we assume. The fourth moments of each variable in w_{ij} are E(w_{iqj}w_{isj}w_{itj}w_{iuj})=0 for all q\neq s, t, u.. uniformly bounded,. 1 and. If $\pi$_{i} is. N_{p}($\mu$_{i}, $\Sigma$_{i}) ( \mathrm{A}‐iii) naturally follows. Also, ,. following assumption. (A‐iv). for. $\Sigma$_{i}, (i=1,2). \displaystle\frac{\mathrm{t}\mathrm{}($\Sigma$_{i}$\Sigma$_{l}) \mathrm{t}\mathrm{}($\Sigma$_{j}^2)}\in(0,\infty). Here, f(p)\in(0, \infty) \infty for a function f. as. as. Aoshima and Yata. E(w_{iqj}^{2}w_{isj}^{2})=. (2014). assume. the. .. p\rightarrow\infty for. i,j, l=1. p\rightarrow\infty denotes that Let. ,. 2.. \displaystyle \lim\inf_{p\rightarrow\infty}f(p)>0. and. \displaystyle \lim\sup_{p\rightarrow\infty}f(p)<. $\kap $_{i}=\displaystle\frac{\mathrm{t}\mathrm{}($\Sigma$_{\dot{l}^2}){n_i}+\frac{\mathrm{t}\mathrm{}($\Sigma$_{1}$\Sigma$_{2}){n_j}+\sum_{i=1}^{2\frac{\mathrm{t}\mathrm{}($\Sigma$_{i}^2)}{2n_{\dot{l}(n_{\dot{l}-1)} for. i(\neq j)=1. 2. Let. ,. n\displaystyle \min=\min\{n_{1}, n_{2}\}. We. assume. the. following assumption:. \displaystyle \frac{($\mu$_{1}-$\mu$_{2})^{T}$\Sigma$_{i}($\mu$_{1}-$\mu$_{2}) {$\kap a$_{i} =o(1). (A‐v). Then, they. have the. Theorem 2.2. (A‐v). Then,. following. (Aoshima. we. have that. p\rightarrow\infty and n_{\min}\rightarrow\infty for i=1 , 2.. result.. and as. as. Yata, 2014). Assume (1.2). Assume also (A ‐iii). \displaystyle \frac{W(x_{0})-( 1)^{i} $\Delta$/2}{\sqrt{$\kap a$_{l} \Rightar ow N(0,1) where. i. to. p\rightarrow\infty and n_{\min}\rightarrow\infty. when x_{0}\in$\pi$_{i}. for. i=1 ,. 〉” denotes the convergence in distribution and N(0,1) denotes as the standard normal distribution.. a. 2,. (2.3). random variable. distributed. Remark 2.3.. From Theorem 2.2, for the classification rule. by (2.1),. it holds that. as. p\rightarrow\infty and n_{\mathrm{m}\mathrm{n}}\rightarrow\infty. e(i)= $\Phi$(\displaystyle \frac{- $\Delta$}{2\sqrt{$\kap a$_{i} )+o(1). when x_{0}\in$\pi$_{i} for i=1 , 2. (2.4).

(5) 5. under the assumptions in Theorem. 2.2, where. denotes the cumulative distribution. $\Phi$. function of the standard normal distribution.. Asymptotic distribution. 3.. In this. Now,. we. (B‐i). section,. we. consider the. a. SSE model. provide the asymptotic distribution of (2.1) under following assumptions for each $\pi$_{i}, i=1 2.. \displaystle\frac{\mathrm{t}\mathrm{}($\Sigma$_{i}^2)-$\lambda$_{1(i)}^{2}$\lambda$_{1(i)}^{2}=o(1) \displaystyle\frac{\sum_{r,s\geq2}^{p}$\lambda$_{r(i)}$\lambda$_{s(i)}E\{(z_{rk(\dot{$\iota$})^{2}-1)(z_{sk(\dot{$\iota$})^{2}-1)\}{n_{i}$\lambda$_{1(i)}^{2}=o(1). fixed. or. p\rightarrow\infty ;. p\rightarrow\infty either when n_{i} is. as. (B‐i). k=1 , is. one. ni i.i.d.. as. N(0,1). of the SSE models.. .. By using the NR method,. by. where. \hat{ $\lambda$}_{j(i)}. SSE model.. n_{i}\rightarrow\infty ;. ( \mathrm{B} ‐iii) z_{1k(i)}, Note that. a. ,. as. (B‐ii). under. \displaystyle\tilde{$\lambda$}_{j(i)}=\hat{$\lambda$}_{j(i)}-\frac{\mathrm{t}\mathrm{r}(S_{in_{i})-\sum_{s=1}^{j}\hat{$\lambda$}_{s(i)}{n_{i}-1j} is the. jth sample eigenvalue. for i. (j=1. 1 , 2.. =. $\lambda$_{j(i)}\mathrm{s}. are. estimated. n_{i}-2 ),. ). Note that. (3.1). \tilde{ $\lambda$}_{j(i)} \geq \tilde{ $\lambda$}_{j(i)}. 0. w.p.1 for. 1, n_{i}-2 j (2012, 2013, 2016) consistency properties when p\rightarrow \infty and n_{i} \rightarrow \infty On the other hand, when p\rightarrow while n_{i}\mathrm{s} are fixed, Ishii et al. (2016) gave the following results. =. .. Yata and Aoshima. showed that. has several. .. Theorem 3.1. (Ishii. 2016).. et al.. Under. (B‐i). and. (B‐ii),. it holds that. as. p\rightarrow\infty. \displaystyle\frac{\tilde{$\lambda$}_{1(i)}{$\lambda$_{1(i)}=\left\{ begin{ar ay}{l} |z_{o1(i)}|^{2}/(n_{i}-1)+o_{p}(1)&when _{i} sfixed,\ 1+o_{p}(1)&when _{i}\rightar ow\infty \end{ar ay}\right. for i=1. ,. 2.. Under. (B‐i). to. (B‐iii),. it holds that. as. (n_{i}-1)\displayst le\frac{\tilde{$\lambda$}_{1(i)}{$\lambda$_{1(i)}\Rightarow$\chi$_{n i}-1^{2} Now,. (B‐iv) (B‐v). we. consider the. p\rightarrow\infty when n_{i} is. for. fiiied. i=1 , 2.. following assumptions.. \displaystyle\frac{$\lambda$_{1( )}{$\lambda$_{1(2)}=1+o(1) h_{1(1)}^{T}h_{1}\text{(}2 \displaystyle\frac{($\mu$_{1}-$\mu$_{2})^{T}$\Sigma$_{i}($\mu$_{1}-$\mu$_{2}) {$\lambda$_{1( )} =o(n_{\min}^{-1}) and. ). =1+o(1). as. as. p\rightarrow\infty.. p\rightarrow\infty and n_{\min}\rightarrow\infty for i=1 , 2.. \infty.

(6) 6. the. (B‐iv) means that the two class share their first eigenspace. One can check validity of (B‐iv) by using a test procedure given by Ishii et al. (2016). Now, we consider the asymptotic distribution of (2.1) under the SSE model, (B‐i).. Let. z_{01(i)}. Note that. result.. =h_{1(i)}^{T}(x_{0}-$\mu$_{i})/$\lambda$_{1(i)}^{1/2} when x_{0}\in$\pi$_{\dot{\mathrm{t} } for i=1 (B‐i), (B- $\iota$ v). Assume. Lemma 3.1.. (B‐v).. and. ,. 2.. Then,. Then,. we. have the. have that. we. following. as. p \rightarrow. oo. and. as. p \rightarrow. \infty. and. n_{\min}\rightarrow\infty. \displaystyle \frac{W(x_{0})-( 1)^{i} $\Delta$/2}{$\lambda$_{1(1)} =z_{01}. when x_{0}\in$\pi$_{i}. From Lemma 3.1. Theorem 3.2.. we. for. have the. Assume. (i ). (\overline{z}_{1(2)}-\overline{z}_{1(1)})+o_{p}(n_{\min}^{-1/2}). i=1 , 2.. following. (B‐i), (B‐iii). to. result.. (B‐v). Then,. have that. we. n_{m\dot{ $\iota$}n}\rightarrow\infty. u_{n}\displaystyle \frac{W(x_{0})-( 1)^{i} $\Delta$/2}{$\lambda$_{1(1)} \Rightar ow U_{1}\times U_{2}. when x_{0}\in$\pi$_{i} where u_{n}. tributed. =. as. (n_{1}^{-1}+n_{2}^{-1})^{-1/2}. N(0,1). and U_{i}s. for i=1 2,. are. ,. mutually independent. random variables dis‐. .. Remark 3.1. From Theorem 3.2, for the classification rule p\rightarrow\infty and n_{\mathrm{m}\mathrm{j}\mathrm{n} \rightar ow\infty. e(i)=P\displaystyle \{U_{1}U_{2}\leq-u_{n}\frac{ $\Delta$}{2$\lambda$_{1(1)} \}+o(1) under the assumptions in Theorem 3.2. One. can. by (2.1),. it holds that. when x_{0}\in$\pi$_{i} for i=1 , 2. estimate $\Delta$. as. (3.2). by. \hat{ $\Delta$}=| \overline{x}_{1n_{1} -\overline{x}_{2n_{2} | ^{2}-\mathrm{t}\mathrm{r}(S_{1n_{1} )/n_{1}-\mathrm{t}\mathrm{r}(S_{2n2})/n_{2}. The estimator. \hat{$\Delta$}. and. \tilde{ $\lambda$}_{1(i)}.. was. given by Aoshima and Yata (2011). Then,. we can. estimate. (3.2) by. Appendix Proof of Lemma 3.1. We. assume. x_{0}\in$\pi$_{1} without loss of. generality.. It holds that. |\displaystyle\overline{x}_{in_{i}-$\mu$_{i}|^{2}-\frac{\mathrm{t}\mathrm{r}(S_{\dot{l}n_{i}){n_{i}=\sum_{s=1}^{p}\sum_{k\neqk}, $\lambda$_{s(i)}\displaystyle\frac{z_{sk(i)}z_{sk'(\dot{$\iota$}) {n_{i}(n_{i}-1)}. (x_{0}-$\mu$_{1})^{T}(\displaystyle \overline{x}_{1n_{1} -$\mu$_{1})=$\lambda$_{1(1)}z_{01(1)}\overline{z}_{1(1)}+\sum_{s=2}^{p}$\lambda$_{s(1)}z_{01(s)}\overline{z}_{s(1)}. ;. (A. 1). ,. (A.2).

(7) 7. H_{1}\mathrm{A}_{1}^{1/2} (z_{01(1)}, z_{01(p)})^{T}. where x_{0}-$\mu$_{1} $\tau$>0 , under (B‐i) and =. (B‐iv),. we. have that. .. By using Chebyshev’s inequality, for. as. E\displayst le\{| sum_{s=1}^{p}\sum_{k\neqk'}\frac{$\lambda$_{s(l)}z_{sk(i)}z_{sk'(\dot{$\iota$}) {n_{i}(n_{i}-1)}|\geq$\tau$n_{\min}^{-1/2}$\lambda$_{1( )}\ leq\frac{\sum_{s -}1^{p}$\lambda$_{s(i)}^{2}{$\tau$^{2}$\lambda$_{1( )}^{2}(n_{i}-1)}\rightarow0 E\displaystyle\{| sum_{s=2}^{p}$\lambda$_{s(1)}z_{0s(1)^{\overline{Z}s(1)}|\geq$\tau$n_{\min}^{-1/2}$\lambda$_{1( )}\ leq\frac{\sum_{s-2}^{p}$\lambda$_{s(1)}^{2}{$\tau$^{2}$\lambda$_{1( )}^{2}\rightar ow0, so. that from. (A.1). and. ;. (A.2). |\displaystyle \overline{x}_{in_{i} -$\mu$_{i}|^{2}-\frac{\mathrm{t}\mathrm{r}(S_{\dot{ $\iota$}n_{i} )}{n_{i} =o_{p}(n_{\min}^{-1/2}$\lambda$_{1(1)}. for i=1 , 2;. (x_{0}-$\mu$_{1})^{T}(\overline{x}_{1n_{1} -$\mu$_{1})=$\lambda$_{1(1)}z_{01(1)}\overline{z}_{1(1)}+o_{p}(n_{\min}^{-1/2}$\lambda$_{1(1)}) Let. $\beta$_{st}=($\lambda$_{s(1)}$\lambda$_{t(2)})^{1/2}h_{s(1)}^{T}h_{t(2)}. for all s, t. .. Then,. we. (A.3). .. write that. (x_{0}-$\mu$_{1})^{T}(\displaystyle\overline{x}_{2n_{2} -$\mu$_{2})=\sum_{s,t\geq1}^{p}$\beta$_{st}z_{0s(1)^{\overline{\mathcal{Z} t(2)} =$\beta$_{1 }z_{01( )}\displaystyle\overline{z}_{1(2)}+\sum_{s=2}^{p}$\beta$_{s1}z_{08(1)}\overline{z}_{1(2)}+\sum_{t=2}^{p}$\beta$_{1t}z_{01( )^{\overline{\mathcal{Z} t(2)} +\displaystyle\sum_{s,t\geq2}^{p}$\beta$_{st}z_{0s(1)^{\overline{Z}t(2)} .. Let. any. p\rightarrow\infty and n_{\mathrm{m}\mathrm{j}\mathrm{n} \rightar ow\infty. $\Sigma$_{i*}=\displaystyle \sum_{s=2}^{p}$\lambda$_{s(i)}h_{s(i)}h_{s(i)}^{T}. for i=1 2. ,. Here,. we. (A.4). have that. E\displaystyle\{(\sum_{s=2}^{p}$\beta$_{s1}z_{0s(1)}\overline{z}_{1(2)} ^{2}\ =\frac{\sum_{s=2}^{p}$\beta$_{s1}^{2} {n_{2} =\frac{$\lambda$_{1(2)}h_{1(2)}^{T}$\Sigma$_{1*}h_{1(2)} {n_{2} \leq\frac{$\lambda$_{1(2)}$\lambda$_{2(1)} {n_{2} E\displaystyle\{(\sum_{t=2}^{p}$\beta$_{1t}z_{01( )^{\overline{Z}t \text{(}2) ^{2}\ =\frac{$\lambda$_{1( )}h_{1( )}^{T}$\Sigma$_{2*}h_{1( )}{n_{2}\leq\frac{$\lambda$_{1( )}$\lambda$_{2( )}{n_{2}. ;. ;. E\displayst le\{( sum_{s,t\geq2}^{p}$\beta$_{st}z_{0s(1)}\overline{z}_{t(2)}^{2}\= frac{\mathrm{t}\mathrm{r}($\Sigma$_{1*}$\Sigma$_{2*}){n_2}\leq\frac{\sqrt{\mathrm{t}\mathrm{r}($\Sigma$_{1*}^{2})\mathrm{t}\mathrm{r}($\Sigma$_{2*}^{2}) {n_2}. Then, by using Chebyshev‘s inequality, for that. as. any $\tau$>0 , under. (B‐i). p\rightarrow\infty and n_{\min}\rightarrow\infty. P(|\displaystyle\sum_{s=2}^{p}$\beta$_{s1}z_{0s}\overline{z}_{1(2)}|>$\tau$n_{\min}^{-1/2}$\lambda$_{1( )} \leq\frac{$\lambda$_{1(2)}$\lambda$_{2(1)}{$\tau$^{2}$\lambda$_{1( )}^{2}\rightar ow0 P(|\displaystyle\sum_{t=2}^{p}$\beta$_{1t}z_{01}\overline{z}_{t(2)}|>$\tau$n_{\min}^{-1/2}$\lambda$_{1( )} \leq\frac{$\lambda$_{1( )}$\lambda$_{2( )}{$\tau$^{2}$\lambda$_{1( )}^{2}\rightar ow0. and. (B‐iv),. ;. ;. P(|\displayst le\sum_{t8,\geq2}^{p}$\beta$_{st}z_{0s}\overline{z}_t(2)}|>$\tau$n_{\min}^{-1/2}$\lambda$_{1( )} \leq\frac{\sqrt{\mathrm{t}\mathrm{}($\Sigma$_{1*}^{2})\mathrm{t}\mathrm{}($\Sigma$_{2*}^{2}) {$\tau$^{2}$\lambda$_{1( )}^{2}\rightarow0.. we. have.

(8) 8. Then, from (A.4). we. have that. (x_{0}-$\mu$_{1})^{T}(\overline{x}_{2n_{2} -$\mu$_{2})=$\beta$_{11}z_{01}\overline{z}_{1(2)}+o_{p}($\lambda$_{1(1)}n_{\min}^{-1/2}) =$\lambda$_{1(1)}z_{01}\overline{z}_{1(2)}+o_{p}($\lambda$_{1(1)}n_{\min}^{-1/2}) Also, under (B‐iv) and (B‐v),. we. have that. as. (A.5). .. p\rightarrow\infty and n_{\min}\rightarrow\infty. P(|($\mu$_{1}-$\mu$_{2})^{T}(x_{0}-$\mu$_{1})|> $\tau$ n_{\min}^{-1/2}$\lambda$_{1(1)}) \displayst le\leq\frac{n_ \mathrm{ }\mathrm{j}\mathrm{n} ($\mu$_{1}-$\mu$_{2})^{T_ $\Sigma$_{1} ($\mu$_{1}-$\mu$_{2}) {$\tau$^{2}$\lambda$_{1( )}^{2} \rightar ow0 P. so. ;. (| $\mu$_{1}-$\mu$_{2})^{T}(\overline{x}_{2n2}-$\mu$_{2})| > $\tau$ n_{\min}^{-1/2}$\lambda$_{1(1)} \displaystyle\leq\frac{($\mu$_{1}-$\mu$_{2})^{T}$\Sigma$_{2}($\mu$_{1}-$\mu$_{2}){$\tau$^{2}$\lambda$_{1( )}^{2}\rightar ow0,. that. ($\mu$_{1}-$\mu$_{2})^{T}(x_{0}-$\mu$_{1})=o_{p}(n_{\min}^{-1/2}$\lambda$_{1(1)})_{\dot{\text{)} } ($\mu$_{1}-$\mu$_{2})^{T}(\overline{x}_{2n_{2} -$\mu$_{2})=o_{p}(n_{\min}^{-1/2}$\lambda$_{1(1)}). (A.6). Note that. W(x_{0})+$\Delta$/2=\displaystyle\frac{1}{2}\sum_{i=1}^{2}(-1)^{\mathrm{i}+1}\{|\overline{x}_{in_{i} -$\mu$_{i}|^{2}-\frac{\mathrm{t}\mathrm{r}(S_{in_{i} )}{n_{i} \} +\displaystyle \sum_{i=1}^{2}(-1)^{i}(x_{0}-$\mu$_{1})^{T}(\overline{x}_{in_{i} -$\mu$_{i}). -($\mu$_{1}-$\mu$_{2})^{T}(x_{0}-$\mu$_{1})+($\mu$_{1}-$\mu$_{2})^{T}(\overline{x}_{2n_{2}}-$\mu$_{2}). .. (A. 7). Then, by combining (A.3), (A.5) and (A.6) with (A.7), under (B‐i), (B‐iv) and (B‐v), holds that. as. \displaystyle\frac{W(x_{0})+$\Delta$/2}{$\lambda$_{1( )} =z_{01( )}(\overline{z}_{1(2)}-\overline{z}_{1( )} +o_{p}(n_{\mathrm{m}\mathrm{j}\mathrm{n} ^{-\mathrm{l}/2}) For the. case. it. p\rightarrow\infty and n_{\min}\rightarrow\infty. when x_{0}\in$\pi$_{2} ,. Proof of Theorem 3.2.. we. have the result. By using. .. similarly. Thus the proof. Lemma 3.1, the result is obtained. is. completed.. straightforwardly.. Acknowledgment I would like to express my sincere. enthusiastic. guidance. and. thank Associate Professor,. gratitude. to Professor Makoto. Aoshima, for his. helpful support project. Kazuyoshi Yata, for his valuable suggestions. to my research. I would also like to.

(9) 9. References Aoshima, M., Yata, K. (2011). Two‐stage procedures for high‐dimensional quential Analysis (Editor’s special invited paper), 30, 356‐399.. data.. Se‐. Aoshima, M., Yata, K. (2014). A distance‐based, misclassification rate adjusted clas‐ sifier for multiclass, high‐dimensional data. Annals of the Institute of Statistical Mathematics, 66, 983‐1010. Aoshima, M., Yata, K. (2015a). Geometric data. Sequential Analysis, 34, 279‐294. Aoshima, M., Yata,. K.. classifier for. multiclass, high‐dimensional. (2015b). High‐dimensional quadratic. classifiers in non‐sparse. settings. arXiv preprint, arXiv:1503.04549.. Aoshima, M., Yata, K. (2017). Two‐sample tests for high‐dimension, strongly spiked eigenvalue models. Statistica Sinica, in press (\mathrm{a}\mathrm{r}\mathrm{X}\mathrm{i}\mathrm{v}:1602.02491) .. Bickel, P.J., Levina, E. (2004). Some theory for Fisher’s linear discriminant function, and some alternatives when there are many more variables than “naive Bayes observations. Bernoulh, 10, 989‐1010. Chan, Y.‐B., Hall, P. (2009). Scale adjustments for classifiers sample size settings. Biometrika, 96, 469‐478. Dudoit, S., Fridlyand, J., Speed,. T.P.. in. high‐dimensional, low. (2002). Comparison ofdiscrimination methods for. the classification of tumors using gene expression data. Journal Statistical Association, 97, 77‐87.. of. the American. Hall, P., Marron, J.S., Neeman, A. (2005). Geometric representation of high dimension, low sample size data. Journal of the Royal Statistical Society, Series B 67, 427− ,. 444.. Hall, P., Pittelkow, Y., Ghosh, M. (2008). Theoretical measures of relative performance of classifiers for high dimensional data with small sample sizes. Journal of the Royal Statistical Society, Series B 70, 159‐173. ,. Ishii, A., Yata, K., Aoshima, M. (2016). Asymptotic properties of the first princi‐ pal component and equality tests of covariance matrices in high‐dimension, low‐ sample‐size context. Journal of Statistical Planning and Inference, 170, 186‐199. Yata, K., Aoshima,. M.. (2012).. Effective PCA for. high‐dimension, low‐sample‐size of Multivariate. data with noise reduction via geometric representations. Journal. Analysis, 105,. 193‐215.. Yata, K., Aoshima, M. (2013). PCA consistency for the power spiked model dimensional settings. Journal of Multivamate Analysis, 122, 334‐354.. in. Yata, K., Aoshima, M. (2016). Reconstruction of a high‐dimensional low‐rank Electronic Journal of Statistics, 10, 895‐917.. matrix.. high‐.

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