Publications by Abel Yimesgen
Assignment 2
2.Carefully explain the differences between the KNN classifier and KNN regression methods. Ans: In the case of KNN regression method the dependent variable should only be numerical (quantitative), whereas KNN classifier could be used when the dependent variable is categorical. A. Scatterplot matrix of all variables from Auto datasets. library(I...
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Assignment 8
5.We have seen that we can fit an SVM with a non-linear kernel in order to perform classification using a non-linear decision boundary. We will now see that we can also obtain a non-linear decision boundary by performing logistic regression using non-linear transformations of thefeatures. Generate a data set with n = 500 and p = 2, such that the...
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Assignment 3
10.A. Produce some numerical and graphical summaries of the Weekly data. Do there appear to be any patterns? ANS: From the outputs of scatter plot shown below the lag variables does correlated each other but there is a strong correlation between Year and Volume. Also about 44% of the data is classified as Down, and 55% is classified as Up. librar...
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Assignment 4
3.We now review k-fold cross-validation. (a)Explain how k-fold cross-validation is implemented. ANS:K-fold cross validation implemented by taking the total observation and dividing it into k non-overlapping groups of length of n/k. The groups act as test and training set. (b)What are the advantages and disadvantages of k-fold crossvalidation rela...
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Assignment 5
For parts (a) through (c), indicate which of i. through iv. is correct. Justify your answer. The lasso, relative to least squares, is: ANS:Lasso is Less flexible and hence will give improved prediction accuracy when its increase in bias is less than its decrease in variance. Repeat (a) for ridge regression relative to least squares. ANS:Ridge...
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Assignment 6
In this exercise, you will further analyze the Wage data set considered throughout this chapter. Perform polynomial regression to predict wage using age. Use cross-validation to select the optimal degree d for the polynomial. What degree was chosen, and how does this compare to the results of hypothesis testing using ANOVA? Make a plot of the re...
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Assignment 7
Consider the Gini index, classification error, and entropy in a simple classification setting with two classes. Create a single plot that displays each of these quantities as a function of ˆpm1. The x axis should display ˆpm1, ranging from 0 to 1, and the y-axis should display the value of the Gini index, classification error, and entropy. Hint...
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