153,402 research outputs found
Maximally selected chi-square statistics and umbrella orderings
No full textBinary outcomes that depend on an ordinal predictor in a non-monotonic way are common in medical data analysis. Such patterns can be addressed in terms of cutpoints: for example, one looks for two cutpoints that define an interval in the range of the ordinal predictor for which the probability of a positive outcome is particularly high (or low). A chi-square test may then be performed to compare the proportions of positive outcomes in and outside this interval. However, if the two cutpoints are chosen to maximize the chi-square statistic, referring the obtained chi-square statistic to the standard chi-square distribution is an inappropriate approach. It is then necessary to correct the p-value for multiple comparisons by considering the distribution of the maximally selected chi-square statistic instead of the nominal chi-square distribution. Here, we derive the exact distribution of the chi-square statistic obtained by the optimal two cutpoints. We suggest a combinatorial computation method and illustrate our approach by a simulation study and an application to varicella data
Monotonicity of Chi-square Test Statistics
No full textThis paper establishes monotonicity of the chi-square test statistic. As the more efficient parameter estimator is plugged into the test statistic, the degrees of freedom of the resulting chi-square test statistic monotonically increase.
Ar-CHI-tecture: Architecture and Interaction
No full textThe rise of ubiquitous computing leads to a natural convergence between the areas of architectural design (the design of buildings, spaces and experience of being in and moving through them) and HCI. We suggest that Architecture and CHI have much to learn from each other in terms of research and practice. This workshop will bring together these communities to explore the benefits of architecture envisioned as integral to an expanded CHI community. The workshop organizers aim to create a framework for future collaboration and identify new directions for research in this multidisciplinary field. This promises significant impacts on both interaction research and its real-world applications
Maximally selected chi-square statistics and binary splits of nominal variables
No full textWe address the problem of maximally selected chi-square statistics in the case of a binary Y variable and a nominal X variable with several categories. The distribution of the maximally selected chi-square statistic has already been derived when the best cutpoint is chosen from a continuous or an ordinal X, but not when the best split is chosen from a nominal X. In this paper, we derive the exact distribution of the maximally selected chi-square statistic in this case using a combinatorial approach. Applications of the derived distribution to variable selection and hypothesis testing are discussed based on simulations. As an illustration, our method is applied to a pregnancy and birth data set
Maximally selected chi-square statistics for at least ordinal scaled variables
No full textThe association between a binary variable Y and a variable X with an at least ordinal measurement scale might be examined by selecting a cutpoint in the range of X and then performing an association test for the obtained 2x2 contingency table using the chi-square statistic. The distribution of the maximally selected chi-square statistic (i.e. the maximal chi-square statistic over all possible cutpoints) under the null-hypothesis of no association between X and Y is different from the known chi-square distribution. In the last decades, this topic has been extensively studied for continuous X variables, but not for non-continuous variables with an at least ordinal measurement scale (which include e.g. classical ordinal or discretized continuous variables). In this paper, we suggest an exact method to determine the distribution of maximally selected chi-square statistics in this context. This novel approach can be seen as a method to measure the association between a binary variable and variables with an at least ordinal scale of different types (ordinal, discretized continuous, etc). As an illustration, this method is applied to a new data set describing pregnancy and birth for 811 babies
Chi-Squared test corresponding to hypothesis <i>H</i><sub>2</sub>.
No full textChi-Squared test corresponding to hypothesis H2.</p
The IEEE symposium on Computers and Communications
No full textISCC 2010 General Chairs: A. Corradi; M. Daneshmad - Technical Program Co-Chairs: P. Bellavista; Chi-Ming Chen; H. Hossanein. Proceedings of the 15th IEEE Symposium on Computers and Communications 2010, Riccione, Italy, June 22-25, 2010
Graduate recital, piano. Chi, C.-H., 1992
No full textRecorded during a live performance at Dalton Center Recital Hall, Western Michigan University, Kalamazoo, Michigan, May 6, 1992, 8:00 p.m., the 545th concert of the School of Music's 1991-1992 season.Chia-Hui Chi, piano.In partial fulfillment of the requirements of the Master of Music degree in piano performance, Western Michigan University, 1992.Information from performance program.Piano sonata, op. 53 / Ludwig van Beethoven -- Ballade in G minor for piano, op. 23 / Frederic Chopin -- Third sonata / Paul Hindemith
- …
