Using 30% of the data for the test set had been a popular heuristic, and it works well with a modest number of examples, such as 100 to 10,000 examples. For big-data machine learning problems, the fraction of data allocated to dev/test sets has been shrinking even as the absolute number of examples in those sets has been growing. Dev/test sets do not need to be excessively large beyond what is needed to evaluate algorithm performance.

70/30 Train/Test Split Heuristic Does Not Apply to Large Datasets

A test set should be big enough to give a confident estimate of the final performance of the system.

Sizing the Test Set for a Confident Performance Estimate

The test set should be large enough to give high confidence in the overall performance of the system.

Test Set Should Support High-Confidence Performance Estimates

A test set is used to evaluate algorithm performance, but not to make decisions about which learning algorithm or parameters to use.

Google

Machine learning is a field that studies how computer systems can utilize experience—typically in the form of data—to improve their performance on specific tasks. It integrates principles from statistics, data mining, and optimization, and is frequently employed as a primary method for implementing artificial intelligence solutions.

Machine Learning

Machine Learning Yearning, a free ebook from Andrew Ng, teaches you how to structure Machine Learning projects.
https://www.deeplearning.ai/machine-learning-yearning/

Note: The content of the book is aligned with the Coursera Deeplearning.ai specialization.  https://www.deeplearning.ai/deep-learning-specialization/ 

Machine Learning Yearning (Deeplearning.ai)

Representational learning is a class of machine learning that focuses on automatically discovering the most appropriate way to represent data. By learning these representations directly from the data, it eliminates the need for manual feature engineering and allows models to effectively process and understand complex inputs.

Representational Learning

Supervised learning learns a function mapping inputs x to outputs y using labeled training examples (x,y). Linear regression, logistic regression, and neural networks are examples of supervised learning algorithms.

Supervised Learning

Kaggle is a popular online platform that hosts machine learning competitions. Each competition centers on a specific dataset, and many are sponsored by stakeholders who offer prizes for the winning solutions. The platform enables direct quantitative comparisons of competing approaches and fosters collaboration by allowing users to interact via forums and share code.

Kaggle Platform

Combining classical machine learning and deep learning within predictive analytics platforms enables users to forecast future trends and behaviors with high precision. These data-driven insights accelerate time-to-value across industries by optimizing courses of action and reducing margins of error, effectively replacing retrospective interpretations with forward-looking decision-making.

Predictive Analytics for Accelerated Decision-Making

A development set, sometimes called a hold-out cross validation set, is used to tune parameters, select features, and make other decisions about the learning algorithm.

Development Set (Dev Set)

Test Set

When multiple evaluation metrics matter, such as accuracy and running time of a learning algorithm, one way to combine them is to define an acceptable value for one metric and then optimize another metric subject to meeting that criterion. In the passage's example, running time is the satisficing metric and accuracy is the optimizing metric.

Optimizing and Satisficing Metrics

For a new machine learning problem, it is very difficult to know in advance which approach will work best. Even experienced machine learning researchers usually try out many dozens of ideas before they discover something satisfactory.

Difficulty of Knowing the Best ML Approach in Advance

Machine learning is a highly iterative process. When building a machine learning system, the author often follows a loop: start with an idea about how to build the system, implement the idea in code, and carry out an experiment that tells how well the idea worked. Based on what is learned, generate more ideas and keep iterating; many dozens of ideas may be tried before finding one that is satisfactory.

Iterative Loop of Machine Learning Development

There are two major sources of error in machine learning: bias and variance. Understanding them helps decide whether adding data and other tactics to improve performance are a good use of time.

Bias and Variance as Two Major Sources of Error

End-to-end deep learning can directly learn outputs that are more complex than a number. With the right labeled input-output pairs, end-to-end learning can sometimes learn outputs such as a sentence, an image, audio, or other outputs richer than a single number.

End-to-End Learning

A pipeline may be flawed if the overall system falls far short of human-level performance even though each individual component is at or near human-level performance given its inputs. This suggests that the pipeline is missing information and should be redesigned.

Machine Learning Pipeline System

Sentiment classification is the problem of recognizing whether text expresses a positive or negative opinion, such as whether an online product review says the writer liked or disliked the product.

Sentiment Classification

Machine learning strategy is the practice of choosing useful directions for improving a machine learning application. It uses clues from the problem to decide what is useful to try and what is not useful to try.

Machine Learning Strategy

Recent progress in deep learning has been driven by data availability and computational scale.

Learn Before

Related

Learn After