The Transformation stage is where data discrepancies are often addressed. During transformation, data is cleaned, normalized, and validated to ensure consistency and reliability. This stage is critical for data quality and consistency in the data warehouse. Extraction involves collecting data, Loading is about data loading into the warehouse, and Data Ingestion is the process of bringing data into the system.

To address the vanishing gradient problem in RNNs, one common technique is to use Long Short-Term Memory (LSTM) networks. LSTMs are a type of RNN that helps mitigate the vanishing gradient problem by preserving and updating information over long sequences. LSTMs are designed to capture long-term dependencies and are more effective than traditional RNNs for tasks where data from distant time steps is important.

The issue where adding more layers to a deep neural network exacerbates the training problem due to diminishing gradients is called "Vanishing Gradient." It occurs when gradients become too small during backpropagation, making it challenging for deep networks to learn intricate patterns in the data.

The "Transformation" stage in the ETL (Extract, Transform, Load) process is responsible for cleaning, validating, and transforming data to ensure its quality. This phase involves data cleaning, data type conversion, and other operations to make the data suitable for analysis and reporting.

When dealing with skewed datasets, the median is preferred for imputation. The median is robust to extreme values and is less affected by outliers than the mean. Using the median as the measure of central tendency helps maintain the integrity of the dataset in the presence of outliers.

Data Engineers are responsible for the efficient collection, storage, and processing of data. They create the infrastructure necessary for Data Scientists and Analysts to work with data effectively.

The measure of the relationship between two variables, ranging from -1 (perfect negative correlation) to 1 (perfect positive correlation), is known as the "correlation coefficient." It quantifies the strength and direction of the linear relationship between variables.

Federated learning trains machine learning models on decentralized data sources without transferring them to a central server. This approach is privacy-preserving and efficient. In contrast, traditional machine learning typically trains models on a single, centralized dataset, which may raise data privacy concerns.

Apache Spark provides the "GraphX" library for graph processing in a distributed environment. GraphX is a part of the Spark ecosystem and is used for graph analytics and computation. It's a powerful tool for analyzing graph data.

Pre-processing in computer vision typically includes steps like resizing, filtering, and transforming an image. It's during this phase that an image is converted into an array of pixel values, making it ready for subsequent analysis and feature extraction.