## Introduction To Machine Learning Models

Machine learning models are software functions that have been trained to recognize certain types of patterns and make predictions. Machine Learning models are used in various fields like finance, retail, healthcare and marketing to learn with the given data and predict future outcomes. These models can be built for and applied to different industries as well.

Machine learning starts with an functional architecture or layout for training. After training what emerges is effectively an algorithm, or a set of steps computers can then use to make predictions when new data is introduced. Models learn from the given datasets in order to derive patterns and make predictions for new data. The five machine learning models we will discuss today are classification models, regression models, clustering, dimensionality reduction, and deep learning.

## Popular Machine Learning Algorithms

There are four main types of machine learning algorithms.

- Supervised learning - the learning model is taught by finding patterns in the data and learns from observations. The operator provides the machine a dataset with known inputs and outputs. The algorithm then makes predictions based on the inputs and known correct answers. The operator corrects these predictions until the learning algorithms operate with high accuracy.
- Semi-supervised - similar to supervised learning; however, it uses labelled and unlabelled data to help the learning model understand the data.
- Unsupervised- machine learning algorithm identifies patterns in data without an answer key or operator to provide instruction.
- Reinforcement learning - teaches the learning algorithms trial and error. The machine is active and adapts its approaches to achieve the best results possible.

## Classification Model

A classification model is a machine learning model that classifies new data into categories. To do this, the model uses patterns from training data to determine which category a particular piece of new data should belong to.

The main benefit of this model is that it can handle both labeled and unlabeled data. This means that the algorithm only needs to be shown an example of what the correct category for a particular piece of new data should be in order to determine how it should be classified.

There are different types of classification models, but the most popular are decision trees and support vector machines.

## Decision Trees

A decision tree is a type of classification model that uses a hierarchy of nodes to classify data. The algorithm starts by identifying a root node, which is the category that all new data will be classified into. From there, the algorithm splits the data into two categories, and determines which category each new piece of data should belong to. This process is repeated until all the data has been classified.

The advantage of using a decision tree is that it is easy to understand and interpret. The disadvantage is that they can be fragile, meaning that they can be easily broken by changes in the input dataset.

### Model Parameters

Once a decision tree has been created, there are several model parameters that can be tuned to improve the accuracy of future predictions. The following is a summary of these model parameters.

### Split Criteria

The split criterion determines how the algorithm should determine which category to place new data into. There are several different split criteria that can be used, but the most common are the entropy and Gini indices.

### Entropy

The entropy criterion measures the amount of uncertainty associated with a particular category. The higher the entropy, the more uncertain the category is.

### Gini Coefficient

The Gini coefficient is a measure of how evenly the data is distributed across the categories. The higher the Gini coefficient, the more even the distribution of data.

### Impurity Measures

After splitting up the dataset into two categories using a split criterion, impurity measures can be used to determine how pure each category is. There are different types of impurity measures that can be used, but the most common are the misclassification error and the Gini impurity.

### Misclassification Error

The misclassification error is the percentage of data that is incorrectly classified into a particular category.

### Gini Impurity

The Gini impurity is a measure of how evenly the data is distributed across the categories. The higher the Gini impurity, the more even the distribution of data.

### Missing Values

When a tree splits a dataset into two categories, it can have a negative impact on accuracy if there are any missing values in the input dataset. Imputation methods can be used to correct this issue by using mean or mode estimates for these missing values.

## Support Vector Machines

Support vector machines (SVMs) are a type of classification model that is similar to decision trees, but has the advantage of being less fragile. Like decision trees, SVMs use a hierarchy of nodes to classify data, but they are able to do this with a much higher accuracy.

In order to create an SVM, a dataset is first divided into two categories: the training data and the testing data. The training data is used to create the model, and the testing data is used to evaluate the accuracy of the model.

The algorithm starts by determining the hyperplane that best separates the two categories. A hyperplane is simply a line or plane that divides a dataset into two categories. The algorithm then calculates the distance of each data point to the hyperplane. The data points that are closest to the hyperplane are classified into the same category, and the data points that are furthest away are classified into the other category.

### Learning Model Parameters

There are several model parameters that can be tuned to improve the accuracy of future predictions. The following is a summary of these model parameters.

### Kernel

The kernel is the function that is used to calculate the distance of each data point to the hyperplane. There are several different types of kernels that can be used, but the most common are the linear kernel and the polynomial kernel.

### Threshold

The threshold is used to determine whether or not the data points are classified into the same category. The data points that are closest to the hyperplane are always included, but if there is no point within some threshold distance of the hyperplane, then the algorithm will classify all the data points on one side of it as part of one group and all those on the other side as part of the other group.

### Iterations

SVMs use a variety of iterations in order to continually improve accuracy and avoid overfitting. Overfitting occurs when the model becomes too complex and begins to fit noise in the data instead of the actual patterns that would allow it to make accurate predictions for future data sets. When it comes time to use the SVM for prediction, the number of iterations that were used to create the model can be reduced in order to improve performance.

### C-Support Vectors

The C-support vectors are a subset of the support vectors that are used to improve the accuracy of predictions. The algorithm calculates the distance of each data point to each of the support vectors, and then selects the support vectors that have the smallest distance. These support vectors are then used to improve the accuracy of predictions.

## Regression Models

Regression models make predictions about a dependent variable based on the value of one or more independent variables. These models are often used to forecast sales volume, forecast election outcomes, and make movie recommendations.

There are several different types of regression models, but the most popular are linear regression and logistic regression.

## Linear Regression

Linear regression is a type of regression model that uses a straight line to predict the value of the dependent variable. The advantage of this model is that it is easy to understand and interpret. The disadvantage is that it can easily be broken by changes in the input dataset.

### Model Parameters

Once a linear regression model has been created, there are several model parameters that can be tuned to improve the accuracy of future predictions. The following is a summary of these model parameters.

### Regression Coefficients

The regression coefficients are numerical weights that are used to multiply the independent variables, so that they can be combined into a single number. The regression coefficients provide insight on which of the independent variables may be most important in predicting the dependent variable.

### Standard Error

The standard error of the regression is used to measure how accurate future predictions will be based on past data. The lower the standard error, the more accurate the predictions will be.

### Residuals

The residuals are the difference between the observed values of the dependent variable and the predicted values of the dependent variable. These residuals can be used to identify any patterns in the data that were not captured by the regression model.

## Logistic Regression

Logistic regression is a type of regression model that is used to predict the probability of a particular event occurring. The advantage of this model is that it can be used to predict binary outcomes, such as whether or not a customer will buy a product. The disadvantage is that it is more complex than linear regression and can be difficult to interpret.

## Clustering

With the rapid evolution of technology, machine learning models are being used to solve business challenges. The most popular algorithm for solving these problems is clustering. Clustering algorithms identify groups of similar data points together and produce patterns within those groups.

The advantage of using clustering algorithms is that they can be used on large datasets to find. Clustering is the process of grouping data points together based on their similarities. There are several different types of clustering algorithms, but the most popular are K-means clustering and hierarchical clustering.

## K-Means Clustering

K-means clustering is a type of clustering algorithm that uses a distance metric to group data points together. The algorithm starts by randomly selecting a number of data points, called the centroids, and then groups the remaining data points together based on their distance from the centroids.

The advantage of this algorithm is that it is fast and easy to implement. The disadvantage is that it can produce clusters that are not well-defined.

## Hierarchical Clustering

Hierarchical clustering is a type of clustering algorithm that starts by placing each data point in its own cluster. Then, the algorithm merges smaller clusters together until there are only a few large clusters left.

The advantage of this model is that it can provide several different levels of detail for each group of data points and can be used to identify outliers. The disadvantage is that it may produce clusters that overlap and merge together.

## Dimensionality Reduction

One of the challenges of machine learning is that the data can often be quite large and complex. This can make it difficult to find patterns and make predictions. Dimensionality reduction is a technique that can be used to reduce the size of the data, so that it is easier to work with.

There are several different types of dimensionality reduction algorithms, but the most popular are principal component analysis (PCA) and t-distributed Stochastic Neighbor Embedding (t-SNE).

## Principal Component Analysis (PCA)

Principal component analysis is a type of dimensionality reduction algorithm that uses a matrix decomposition to reduce the number of dimensions in the data. The algorithm starts by computing the eigenvalues and eigenvectors of the data matrix. Then, the first eigenvector is chosen as the first principal component and the second eigenvector is chosen as the second principal component.

The advantage of this algorithm is that it can make predictions even on large datasets. The disadvantage is that it can produce different results when run multiple times on the same dataset.

## Deep Learning

Deep learning is a subset of artificial intelligence that uses artificial neural networks to automate tasks. The algorithm is programmed with structured data and has the ability to learn on its own to improve its performance.

A research team at Microsoft conducted the first successful deep learning experiment in 2008, where they trained an algorithm to recognize handwritten digits from the MNIST database.

The advantage of deep learning is that it can be used for complicated tasks like image recognition, speech recognition, language translation, and emotion detection. The disadvantage of deep learning is that it requires large amounts of data sets to train the algorithm with.

## Machine Learning Conclusion

Machine Learning Models are an important part of artificial intelligence. Using algorithms, they can learn from the given data to make predictions for future behavior with high accuracy.

Machine learning models when it comes to data modeling is a subset of artificial intelligence that uses algorithms in order to categorize large datasets and form predictions for future behavior with high accuracy. The algorithm learns from the given datasets in order to derive patterns and make predictions for new data. The advantage of using clustering algorithms is that they can be used on large datasets to find groupings or clusters based on their similarities.

If you'd like to learn more about machine learning models or want help implementing these principles in your own company, talk to one of our DATA BOSSES! Our team would be happy to partner with you and create a roadmap that provides you with predictive analytics and a design engine.