- Naive Bayes
- Natural Language Processing (NLP)
- Nearest Neighbor
- Negative Sampling
- Network Compression
- Network Science
- Network Topology
- Network Visualization
- Neural Architecture Search
- Neural Collaborative Filtering
- Neural Differential Equations
- Neural Machine Translation
- Neural Networks
- Neural Style Transfer
- Neural Tangent Kernel
- Neuroevolution
- Neuromorphic Computing
- Node Embedding
- Noise Reduction Techniques
- Non-autoregressive models
- Non-negative Matrix Factorization
- Non-parametric models
- Nonlinear Dimensionality Reduction
- Nonlinear Regression
- Nonparametric Regression
- Normalization
- Novelty Detection
- Numerical Methods
- Numerical Optimization

# What is Negative Sampling

**Understanding Negative Sampling in Machine Learning**

When it comes to training a machine learning model, one of the most crucial tasks is preparing the training data. The quality of the training data has a significant impact on the accuracy and reliability of the model. However, for some problems, collecting enough training data can be difficult or even impossible. This is where negative sampling comes in handy, a technique used to generate negative examples that can help improve the performance of a machine learning model.

**What is Negative Sampling?**

Negative sampling is a type of data sampling technique used in many machine learning models, including neural networks and word embeddings, to train models on imbalanced datasets. Imbalanced datasets are common in many machine learning problems, wherein the number of negative examples is significantly higher than the number of positive examples, making it challenging for the model to learn effectively. Negative sampling helps mitigate this problem by generating negative examples that model the statistical properties of the data and balance the positive and negative examples.

**How Negative Sampling Works?**

In negative sampling, the goal is to sample negative examples that are similar to the training examples in the context of the model. The technique works by selecting a few negative examples at random from a predefined distribution. However, choosing random negative examples can often lead to poor performance. Instead, negative examples are generated using a specialized algorithm, which aims to maximize the cosine distance between the negative examples and the positive examples while minimizing the computational complexity.

**Advantages of Negative Sampling**

**Improves Model Performance:**Negative sampling helps improve model performance by increasing the accuracy and reducing the training time of the model. This technique reduces the overall training time by decreasing the number of negative examples the model needs to evaluate.**Reduced Complexity:**Negative sampling reduces the computational complexity of the model by decreasing the number of negative examples that the model needs to evaluate. This technique can significantly reduce the training time and allows the model to be trained on more extensive datasets without compromising the model's performance.**Better Results on Sparse Data:**Negative sampling works particularly well on sparse data where the number of positive examples is scarce, making it challenging to build a comprehensive model with the available data. This technique improves the model's performance by generating effective negative examples that balance the data distribution and ensure the model can make accurate predictions even on infrequent examples.

**How Negative Sampling is Implemented?**

The implementation of negative sampling varies depending on the type of model and the data being used. However, the general approach to implementing negative sampling is as follows:

**Determine the Training Data:**The first step in implementing negative sampling is to determine the training data and identify the positive and negative examples. The positive examples are the correct examples that the model should predict, while the negative examples are the incorrect examples used to balance the data distribution.**Select Negative Examples:**Once the positive and negative examples are identified, the next step is to select negative examples using a specialized algorithm that generates new examples that are similar to the positive examples in the context of the model.**Train the Model:**After selecting the negative examples, the next step is to train the model using a technique such as backpropagation or stochastic gradient descent. The training process involves adjusting the weights of the model based on the examples' correctness until the model converges and provides the desired performance.

**Examples of Negative Sampling**

Negative sampling is used in many machine learning applications, including:

**Word Embeddings:**Negative sampling is used to train word embedding models, wherein the goal is to learn low-dimensional representations of words that capture their semantic and syntactic properties. In word embeddings, negative sampling is used to generate negative examples for each word, improving the model's accuracy and reducing the training time.**Recommendation Systems:**Negative sampling is used in recommendation systems, where the training data consists of clickstream data, indicating which items were clicked and which were not. Negative sampling generates negative examples of items that were not clicked but could have been selected as potential recommendations by the model.**Data Representation:**Negative sampling is used in data representation, where the goal is to represent high-dimensional datasets in low-dimensional space while preserving the data's structure and information. Negative sampling generates negative examples that model the statistical properties of the data, improving the model's accuracy and the resulting representation.

**Conclusion**

Negative sampling is a powerful technique that has significant practical implications for machine learning applications. The technique's strength lies in its ability to effectively balance imbalanced datasets by generating negative examples that improve the model's accuracy and reduce the training time. Although negative sampling can be challenging to implement, it is a valuable tool for machine learning practitioners seeking to improve their models' performance.