Macro-averaging computes the average metric score for each class, treating all other classes as the "negative" class. It provides an equal weight to each class and is useful when you want to assess the model's overall performance while giving equal importance to each class, regardless of class size. Macro-averaging can be particularly useful in imbalanced multi-class classification problems.

The Box Plot, also known as a box-and-whisker plot, considers the spread of data points around the median and helps identify outliers based on the interquartile range (IQR). Outliers are data points that fall outside the whiskers of the box plot. Z-Score is used for standardization, One-Hot Encoding is used for categorical variables, and K-Means Clustering is a clustering technique and not used for identifying outliers.

In Big Data processing, the first blank should be filled with "Filter," and the second blank with "Join." Filtering and sorting are common operations in data preparation, while aggregations and transformations are typically done using join operations.

The ReLU activation function is known for mitigating the vanishing gradient problem, which is a common issue in deep learning. ReLU allows gradients to flow more freely during backpropagation, making it easier to train deep neural networks.

In Tableau, a "Workbook" is where you can connect to various data sources, design visualizations, and create a unified view of your data. It serves as a container for creating and organizing your data visualizations and analyses.

In L2 regularization (Ridge), the penalty is proportional to the square of the magnitude of the coefficients. This regularization technique adds a penalty term to the loss function based on the sum of squared coefficients, which helps prevent overfitting by discouraging large coefficients.

Standard Deviation is a measure of the spread or variability of data points around the mean. It quantifies how much individual data points deviate from the average, making it a crucial concept in understanding data variability and distribution.

The main function of Hadoop's MapReduce is "Distributed data processing." MapReduce is a programming model and processing technique used to process and analyze large datasets in a distributed and parallel manner.

Gradient Boosting is an ensemble method that adjusts weights for misclassified instances in iterative training. It aims to correct the errors made by the previous models in the ensemble, with a focus on improving prediction accuracy. This method is particularly effective in building strong predictive models by iteratively focusing on the data points that are challenging to classify correctly.

Apache Spark is the most suitable choice for real-time data processing and analytics. It offers in-memory processing, which allows for fast data analysis, making it ideal for providing instant recommendations based on user behavior. Apache Kafka is used for data streaming, not real-time analytics. Hadoop and MySQL are not optimized for real-time processing.