TIL Cost Functions permalink

I’m excited to have started Andrew Ng’s Machine Learning class oun Coursera over the weekend! I hope to learn how to apply machine learning to my decision-making process to make better, more informed decisions.

I’ve only gone through the first few lectures which have reacquainted me with basic machine learning concepts:

• supervised vs unsupervised learning
• regression, classification, and clustering
• parameters, features, variables and labels
• linear algebra and matrix multiplication

But the biggest thing I’ve learned so far is what a cost function is and why it is important. A cost function is an algorithm that measures the accuracy of the algorithm in your model (otherwise know as your hypothesis). This cost function is an important part of the learning process because it helps you quickly identify the optimal algorithm based on your training data.

The class went through building a linear regression algorithm that used a mean squared error cost function to evaluate how using different function parameters affected the accuracy of the algorithm.