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The Spanish economic crisis has led to a significant reduction in housing sales, and therefore, there has been a decrease in housing prices. In this paper, we analyze changes in the average housing price throughout Spain. We use quarterly data from a random sample of 150 municipalities from the first quarter (Q1) of 2005, before the financial crisis started, to Q1 2010. Our analysis uses generalized estimating equation and generalized linear mixed model approaches. Data published for Q2, Q3, and Q4 2010 are compared with the data fitted using these models. Finally, the methods are compared with time‐series models. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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In accelerated life tests (ALTs), test units are often tested in multiple test chambers along with different stress conditions. The nonhomogeneity of test chambers precludes the complete randomized experiment and may affect the life‐stress relationship of the test product. The chamber‐to‐chamber variation should be taken into account for ALT planning so as to obtain more accurate test results. In this paper, planning ALTs under a nested experimental design structure with random test chamber effects is studied. First, by a 2‐phase approach, we illustrate to what extent different test chamber assignments to stress conditions may impact the estimation of unknown parameters. Then, D‐optimal test plans with 2 test chambers are considered. To construct the optimal design, we establish the generalized linear mixed model for failure‐time data and apply a quasi‐likelihood method, where test chamber assignments, as well as other decision variables that are required for planning ALTs, are simultaneously determined. 相似文献