| 1. |
|
|
| 2. |
- Ahmad, M. Rauf, et al.
(författare)
-
A U-statistics Based Approach to Mean Testing for High Dimensional Multivariate Data Under Non-normality
- 2011
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- A test statistic is considered for testing a hypothesis for the mean vector for multivariate data, when the dimension of the vector, p, may exceed the number of vectors, n, and the underlying distribution need not necessarily be normal. With n, p large, and under mild assumptions, the statistic is shown to asymptotically follow a normal distribution. A by product of the paper is the approximate distribution of a quadratic form, based on the reformulation of well-known Box's approximation, under high-dimensional set up.
|
|
| 3. |
- Ahmad, M. Rauf, et al.
(författare)
-
Some Tests of Covariance Matrices for High Dimensional Multivariate Data
- 2011
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Test statistics for sphericity and identity of the covariance matrix are presented, when the data are multivariate normal and the dimension, p, can exceed the sample size, n. Using the asymptotic theory of U-statistics, the test statistics are shown to follow an approximate normal distribution for large p, also when p >> n. The statistics are derived under very general conditions, particularly avoiding any strict assumptions on the traces of the unknown covariance matrix. Neither any relationship between n and p is assumed. The accuracy of the statistics is shown through simulation results, particularly emphasizing the case when p can be much larger than n. The validity of the commonly used assumptions for high-dimensional set up is also briefly discussed.
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
- Krebs, Alice, et al.
(författare)
-
Template for the Description of Cell-Based Toxicological Test Methods to Allow Evaluation and Regulatory Use of the Data
- 2019
-
Ingår i: Altex. - : ALTEX Edition. - 1868-596X .- 1868-8551. ; 36:4, s. 682-699
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Only few cell-based test methods are described by Organisation for Economic Co-operation and Development (OECD) test guidelines or other regulatory references (e.g., the European Pharmacopoeia). The majority of toxicity tests still falls into the category of non-guideline methods. Data from these tests may nevertheless be used to support regulatory decisions or to guide strategies to assess compounds (e.g., drugs, agrochemicals) during research and development if they fulfill basic requirements concerning their relevance, reproducibility and predictivity. Only a method description of sufficient clarity and detail allows interpretation and use of the data. To guide regulators faced with increasing amounts of data from non-guideline studies, the OECD formulated Guidance Document 211 (GD211) on method documentation for the purpose of safety assessment. As GD211 is targeted mainly at regulators, it leaves scientists less familiar with regulation uncertain as to what level of detail is required and how individual questions should be answered. Moreover, little attention was given to the description of the test system (i.e., cell culture) and the steps leading to it being established in the guidance. To address these issues, an annotated toxicity test method template (ToxTemp) was developed (i) to fulfill all requirements of GD211, (ii) to guide the user concerning the types of answers and detail of information required, (iii) to include acceptance criteria for test elements, and (iv) to define the cells sufficiently and transparently. The fully annotated ToxTemp is provided here, together with reference to a database containing exemplary descriptions of more than 20 cell-based tests.
|
|
| 7. |
|
|
| 8. |
- Ohlson, Martin, 1977-, et al.
(författare)
-
More on the Kronecker Structured Covariance Matrix
- 2011
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In this paper the multivariate normal distribution with a Kronecker product structured covariance matrix is studied. Particularly, estimation of a Kronecker structured covariance matrix of order three, the so called double separable covariance matrix. The estimation procedure, suggested in this paper, is a generalization of the procedure derived by Srivastava et al. (2008), for a separable covariance matrix. Furthermore, the restrictions imposed by separability and double separability are discussed.
|
|
| 9. |
- Ohlson, Martin, et al.
(författare)
-
The Multilinear Normal Distribution:Introduction and Some Basic Properties
- 2011
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In this paper, the multilinear normal distribution is introduced as an extension of the matrix-variate normal distribution. Basic properties such as marginal and conditional distributions, moments, and the characteristic function, are also presented. The estimation of parameters using a flip-flop algorithm is also briefy discussed.
|
|
| 10. |
|
|
