tailieunhanh - Data Mining and Knowledge Discovery Handbook, 2 Edition part 25

Data Mining and Knowledge Discovery Handbook, 2 Edition part 25. Knowledge Discovery demonstrates intelligent computing at its best, and is the most desirable and interesting end-product of Information Technology. To be able to discover and to extract knowledge from data is a task that many researchers and practitioners are endeavoring to accomplish. There is a lot of hidden knowledge waiting to be discovered – this is the challenge created by today’s abundance of data. Data Mining and Knowledge Discovery Handbook, 2nd Edition organizes the most current concepts, theories, standards, methodologies, trends, challenges and applications of data mining (DM) and knowledge discovery. | 220 Richard A. Berk Consider now an application of the generalized additive model. For data described earlier Figure shows the relationship between number of homicides and the number executions a year earlier with state and year held constant. Indicator variables are included for each state to adjust for average differences over time in the number of homicides in each state. For example states differ widely in population size which is clearly factor in the raw number of homicides. Indicator variables for each state control for such differences. Indicator variables for year are included to adjust for average differences across states in the number of homicides each year. This controls for year to year trends for the country as a whole in the number of homicides. There is now no apparent relationship between executions and homicides a year later except for the handful of states that in a very few years had a large number of executions. Again any story is to be found in a few extreme outliers that are clearly atypical. The statistical point is that one can accommodate with GAM both smoother functions and conventional regression functions. Figure shows the relationship between number of homicides and 1 the number executions a year earlier and 2 the population of each state for each year. The two predictors were included in an additive fashion with their functions determined by smoothers. The role of execution is about the same as in Figure although at first glance the new vertical scale makes it looks a bit different. In addition one can see that homicides increase monotonically with population size as one would expect but the rate of increase declines. The very largest states are not all that different from middle sized states. Recursive Partitioning Recall again equation reproduced below for convenience as equation p Mj f x EE Pjmhjm x j 1m 1 An important special case sequentially includes basis functions that contribute to .