Machine learning is a field of artificial intelligence that has seen rapid growth in recent years. It has the potential to make a significant impact on many aspects of our lives, from healthcare to business decision-making. However, many people are still unclear about what machine learning is and how it works. In this blog post, we will provide a brief overview of machine learning and its potential applications.
First off, what is machine learning? At its core, machine learning is an area of computer science that provides computers with the ability to learn without being explicitly programmed. This allows machines to “ figure things out” on their own, by imitating the way humans learn. For example, a self-driving car can be taught to identify and avoid objects that are likely to cause a collision. Given enough driving experience and feedback, the automated car learns how to drive autonomously. The important thing to note here is that no human needs to tell the car how to recognize objects or how to react to them —it will learn these things on its own, or at least with little human intervention beyond training the model.
There are a few key concepts that we need to understand in order to fully appreciate machine learning. Perhaps the most important concept to understand is that machine learning is not magic. If you feed a machine learning algorithm a data set with no predictive power, then the algorithm will not be able to make accurate predictions about new examples. Even the most powerful machine learning algorithms are based on models of the systems that they are learning from, and if you simply provide these algorithms with incorrect information, then they cannot perform well!
Producing a data set with predictive power requires a careful process known as data pre-processing. During data pre-processing, we typically remove the unnecessary information from the raw data to make it suitable for analysis. This information might include things like missing data or mislabeled data. Once the preprocessing is complete, the data can be analyzed for predictive power. If the data set is determined to have reasonable predictive power, an appropriate model can be applied to predict new values that were not included in the original training data. Ideally, this process will result in a model that accurately predicts the values that were not included in the original dataset.
Now that we have a basic understanding of machine learning, let’s take a look at some of the more commonly used algorithms.:
linear regression is one of the simplest machine learning algorithms. This model is used to predict a continuous dependent variable based on one or more independent variables. For example, we might use linear regression to predict the price of a house based on its size, number of bedrooms, and number of bathrooms. Once the data set becomes more complex, we can use more sophisticated models that are capable of handling nonlinear relationships.
One of the most commonly -used types of machine learning algorithms is the logistic regression classifier. This model is used to analyze binary classification problems where the output variable is a label that indicates whether a data instance belongs to one group or another group. In this model, the dependent variable is predicted by a linear combination of independent variables that are either continuous (like age and income) or discrete like gender and race. One of the weaknesses of this model is that the model cannot account for nonlinearity in the relationship between the dependent variable and the independent variables.
K nearest neighbors is another common type of machine learning algorithm. As you might guess from the name, this model uses the concept of a "K" number of nearest neighbors. If we use four nearest neighbors for this model, there are four other data points in the model whose values are predicted based on the values of the input points. We can compute the distances between the input points and the four neighbors and then compute the probabilities for each neighbor. A slightly more sophisticated version of the k nearest neighbors algorithm is theBoosting algorithm. The boosting algorithm is used to improve the performance of a model by using a feedback loop. It builds several models from a large set of data and then applies them in turn to the original training set to refine the overall model. One of the weaknesses of this approach is that it requires more computational resources than a traditional regression approach.
One of my favorite models is the random forest classifier. This model is used to predict discrete values that are not easily classified using a single classifier. In order to understand the random forest classifier, it's important to understand the decisions tree model. A decision tree is a binary classifier that splits the data into two groups based on a certain criterion, such as whether the price of a house is over $1M. Each decision point in the decision tree can be thought of as a tree node that partitions the set of training data into two branches. Decision trees are easy to construct and provide intuitive explanations for how a decision is made. A random forest is a more sophisticated version of the decision tree. In a random forest , rather than having a single decision tree, we have an ensemble of trees, each of which votes on the class of each training data point. This creates an optimization problem where we are looking for the combination of trees that provides the most consistent prediction across the data set. Although decision trees can be built to predict values in a training set with a high degree of accuracy, random forest models tend to provide better predictions in a wider range of situations, also known as generalizing well.
Support vector machines (SVMs) are a class of machine learning models that are also popular for classification problems. SVMs are similar to decision trees in that they are a type of binary classifier. However, rather than having a single decision tree, an SVM has several mini-classifiers that are combined to create the final classification. This method allows each feature of the data to have its own corresponding weight or importance, and this allows the classifier to capture complex non-linear relationships between variables. One of the weaknesses of SVMs is that they do not perform well when the features are highly correlated. However, SVMs are a powerful tool that can sometimes be used to solve difficult classification problems when other methods have failed.
In this blog, we've covered a few different types of classifiers that are commonly used for classification problems in business. While many of these methods focus on single-category classification problems, there are also many methods for multi-category classifications, and most models have variations and parameters that can be fine tuned to a specific problem. In general, it is best practice to use more than one model from a toolkit in order to take advantage of different strengths that each method brings. The data science and machine learning landscape is always changing with new innovations emerging on a regular basis; therefore, it is important to keep an open mind and continually look for new techniques that can improve the performance of your predictive models. However, nearly all machine learning projects start with an analysis of the data to determine if it has any predictive value. If we fail to skip this step, we may be left with the old adage of garbage in, garbage out.