Regression Model for Ames Iowa Housing Prices Using Python Take 4

Template Credit: Adapted from a template made available by Dr. Jason Brownlee of Machine Learning Mastery.

SUMMARY: The purpose of this project is to construct a prediction model using various machine learning algorithms and to document the end-to-end steps using a template. The Ames Iowa Housing Prices dataset is a regression situation where we are trying to predict the value of a continuous variable.

INTRODUCTION: Many factors can influence a home’s purchase price. This Ames Housing dataset contains 79 explanatory variables describing every aspect of residential homes in Ames, Iowa. The goal is to predict the final price of each home.

In iteration Take1, we established the baseline mean squared error for further takes of modeling.

In iteration Take2, we converted some of the categorical variables from nominal to ordinal and observed the effects of the change.

In iteration Take3, we examined the feature selection technique of attribute importance ranking by using the Gradient Boosting algorithm. By selecting only the most important attributes, we decreased the processing time and maintained a similar level of RMSE compared to the baseline.

In this iteration, we will examine the feature selection technique of recursive feature elimination (RFE) by using the Gradient Boosting algorithm. By selecting up to 50 attributes, we hope to decrease the processing time and maintain a similar level of RMSE compared to the baseline.

ANALYSIS: The baseline performance of the machine learning algorithms achieved an average RMSE of 31,172. Two algorithms (Ridge Regression and Gradient Boosting) achieved the top RMSE metrics after the first round of modeling. After a series of tuning trials, Gradient Boosting turned in the best overall result and achieved an RMSE metric of 24,165. By using the optimized parameters, the Gradient Boosting algorithm processed the test dataset with an RMSE of 21,067, which was even better than the prediction from the training data.

From iteration Take2, Gradient Boosting achieved an RMSE metric of 23,612 with the training dataset and processed the test dataset with an RMSE of 21,130. Converting the nominal variables to ordinal did not have a material impact on the prediction accuracy in either direction.

From iteration Take3, Gradient Boosting achieved an RMSE metric of 24,045 with the training dataset and processed the test dataset with an RMSE of 21,994. At the importance level of 99%, the attribute importance technique eliminated 222 of 258 total attributes. The remaining 36 attributes produced a model that achieved a comparable RMSE to the baseline model. The processing time for Take2 also reduced by 67.90% compared to the Take1 iteration.

From iteration Take4, Gradient Boosting achieved an RMSE metric of 23,825 with the training dataset and processed the test dataset with an RMSE of 21,898. The RFE technique eliminated 208 of 258 total attributes. The remaining 50 attributes produced a model that achieved a comparable RMSE to the baseline model. The processing time for Take3 also reduced by 1.8% compared to the Take1 iteration.

CONCLUSION: For this iteration, the Gradient Boosting algorithm achieved the best overall results using the training and testing datasets. For this dataset, Gradient Boosting should be considered for further modeling.

Dataset Used: Kaggle Competition – House Prices: Advanced Regression Techniques

Dataset ML Model: Regression with numerical and categorical attributes