How to make predictions with machine learning models?

Sometimes you might be wondering how it is possible to make predictions with machine learning models. Well, in this short article, we will understand step by step how machine learning models make predictions. Moreover, this article is going to be purely theoretical but if you want to understand how the specific model works and make predictions, you can check the implementation of that model from the list here.

Introduction to Predictive models

Predictive modeling is a key aspect of machine learning and is the process of using a trained model to make predictions on new data. This is an important task in many fields, such as finance, healthcare, and marketing, as it allows businesses to make informed decisions and take appropriate actions based on predicted outcomes.

There are many different machine learning models (LightGBM, CatBoost, Decision trees, KNN, etc) that can be used for predictive modeling, and the choice of model depends on the specific problem at hand and the nature of the data. Some common types of models include linear regression, logistic regression, decision trees, random forests, support vector machines, and neural networks.

In this article, we will walk through the process of using a machine-learning model to make predictions. We will cover the following steps:

• Preparing the data
• Splitting the data into training and test sets
• Choosing a machine learning model
• Training the model
• Making predictions with the model
• Evaluating the model
• Fine-tuning the model

Let us now jump into each of these steps and understand each of them one by one.

Preparing data for Machine learning model

Before we can start training a machine learning model, we need to prepare the data that we will use. This usually involves the following steps:

• Collecting and gathering the data
• Cleaning and preprocessing the data
• Exploring and visualizing the data

Collecting and Gathering the Data: The first step in preparing the data is to collect and gather the data that we will use. This may involve scraping data from websites, collecting data from sensors or devices, or importing data from databases or files.

Cleaning and Preprocessing the Data: Once we have collected the data, the next step is to clean and preprocess it. This may involve removing missing or invalid data, handling outliers, and converting categorical data into numerical form.

Exploring and Visualizing the Data: After the data has been cleaned and preprocessed, we can explore and visualize it to gain insights and understand the relationships between different variables. This can be done using techniques such as histograms, scatter plots, and box plots.

Splitting the Data into Training and Test Sets

Once the data has been prepared, the next step is to split it into training and test sets. The training set is used to train the machine learning model, while the test set is used to evaluate the model’s performance.

There are several ways to split the data, but a common method is to use a random split, where a portion of the data is randomly selected for the training set and the remaining data is used for the test set. The size of the training and test sets can vary, but a common split is to use 80% of the data for training and 20% for testing. You can use sklearn split function to divide the dataset into testing and training parts.

Choosing a Machine Learning Model

Choosing a machine learning model can be a daunting task, especially if you are new to the field of machine learning. There are many different types of machine learning models to choose from, each with its own strengths and weaknesses. Here are a few things to consider when choosing a machine learning model:

1. The type of problem you are trying to solve: Different machine learning models are better suited to different types of problems. For example, decision trees are often used for classification problems, while linear regression is often used for regression problems.
2. The size and quality of your data: Some machine learning models require a large amount of data to be effective, while others can work well with smaller datasets. The quality of your data is also important, as dirty or biased data can negatively impact the performance of your model.
3. The amount of time and resources you have available: Some machine learning models can be very computationally intensive and may require significant time and resources to train. Be sure to consider the resources you have available when choosing a model.
4. The level of interpretability you need: Some machine learning models, such as decision trees, are relatively easy to interpret and understand, while others, such as neural networks, can be more difficult to interpret. If you need to be able to explain the decisions made by your model, you may want to choose a model that is more interpretable.
5. Your familiarity with the model: If you are familiar with a particular machine learning model and feel comfortable using it, you may be more likely to achieve good results with it. On the other hand, if you are not familiar with a model, it may take you longer to get up to speed and achieve good results.

Ultimately, the best machine learning model for your problem will depend on the specific characteristics of your problem and your available resources. It may be helpful to try out a few different models and compare their performance to determine which one works best for your needs

Training the Model

Training a machine learning model involves feeding it a large amount of data and adjusting the model’s parameters to minimize the error between the model’s predictions and the ground truth. There are a few key steps to follow when training a machine learning model:

1. Preprocess the data: Before training a model, it is usually necessary to preprocess the data to get it into a suitable form. This may involve cleaning the data, normalizing numerical values, and converting categorical values into numerical form.
2. Split the data into training and testing sets: It is important to evaluate the performance of the model on unseen data, so it is common to split the data into a training set and a testing set. The model is trained on the training set and evaluated on the testing set.
3. Choose an appropriate evaluation metric: Different types of machine learning problems have different appropriate evaluation metrics. For example, in a classification problem, accuracy might be a good evaluation metric, while in a regression problem, mean squared error might be a good evaluation metric.
4. Choose an appropriate model: Based on the characteristics of the problem and the data, choose a machine learning model that is appropriate for the task.
5. Train the model: Use the training data to adjust the model’s parameters to minimize the chosen evaluation metric. This may involve adjusting the learning rate, the number of hidden layers in a neural network, or other hyperparameters.
6. Evaluate the model: Use the testing data to evaluate the performance of the trained model. Compare the model’s predictions to the ground truth and calculate the chosen evaluation metric.
7. Fine-tune the model: If the model’s performance is not satisfactory, try adjusting the model’s hyperparameters or trying a different model to see if performance can be improved.

Training a machine learning model requires a good understanding of the underlying algorithms and a strong grasp of the principles of machine learning. It can be a time-consuming process, but the results can be very rewarding.

Make predictions with machine learning models

Once a machine learning model has been trained, it can be used to make predictions on new, unseen data. This process is often referred to as “inference.” In this part, we used the testing data that we have split in the data splitting part.

To make predictions with a machine learning model, you will need to follow these steps:

1. Preprocess the data: The data that you want to make predictions on should be cleaned and formatted in the same way as the training data. This is important because the model expects the data to be in a certain format and may not work properly if the data is not formatted correctly.
2. Load the trained model: You will need to load the trained model into your programming environment. This may involve loading the model weights and biases, as well as any other necessary information.
3. Make the predictions: Use the model to make predictions on the new data. This may involve passing the data through the model’s prediction function and using the trained model to generate output.
4. Evaluate the predictions: Compare the model’s predictions to the ground truth (if available) and evaluate the model’s performance using an appropriate evaluation metric.

It is important to note that the model’s predictions may not always be accurate, and it is important to carefully evaluate the performance of the model to ensure that it is making reliable predictions.

Evaluating the model

Once the model has made predictions, it is time to evaluate the performance of the model in order to see how well the predictions are. There are many ways to evaluate a machine learning model, and the specific method used will depend on the type of model and the task it is being used for. Some common evaluation metrics for different types of models include:

• Classification models:
  • Accuracy: the proportion of correct predictions made by the model.
  • Precision: the proportion of true positive predictions among all positive predictions made by the model.
  • Confusion Matrix: This is used to analyze correctly classified and incorrectly classified classes visually.
  • Recall: the proportion of true positive predictions among all actual positive examples.
  • F1 score: the harmonic mean of precision and recall.
  • AUC-ROC: the area under the receiver operating characteristic curve, which plots the true positive rate against the false positive rate.
• Regression models:
  • Mean absolute error: the average difference between the predicted values and the actual values.
  • Mean squared error: the average of the squared differences between the predicted values and the actual values.
  • R2 score: the proportion of the variance in the target variable that is explained by the model.

It is important to evaluate a model using a variety of metrics and to consider the context in which the model will be used when deciding which evaluation metrics are most relevant. For example, a model that is used to predict whether a patient has a disease may need to have high precision, even if it means sacrificing some recall, to avoid misdiagnosing healthy patients as sick. On the other hand, a model that is used to identify spam emails may need to have a high recall, even if it means sacrificing some precision, to avoid missing any spam emails.

Hyperparameter tuning of the model

Fine-tuning a machine learning model involves adjusting the hyperparameters and/or the architecture of the model in order to improve its performance on a specific task. There are several techniques that can be used to fine-tune a model, including:

1. Grid search: this involves specifying a grid of hyperparameter values and training the model for each combination of values, then selecting the combination that performs best.
2. Random search: this involves sampling random combinations of hyperparameter values and training the model for each combination, then selecting the combination that performs best.
3. Bayesian optimization: this involves using Bayesian techniques to search for the optimal combination of hyperparameter values.
4. Model architecture search: this involves using an automated process to search for the optimal architecture of the model, such as the number of layers or the number of units in each layer.

It is important to fine-tune a model on a separate validation set, rather than the training set, to avoid overfitting. It is also important to use cross-validation when fine-tuning a model to ensure that the results are reliable.

Summary

In this short article, we learned how we can make predictions with machine learning models. We discussed each and every step from data filtering to hyperparameter tuning of the model. If you want to learn to make predictions with machine learning models using Python, you can check the list of implemented models in Python from here.