Machine Learning Fundamentals: Models, Bias-Variance, Metrics
1. The Three Goals of Modeling
| Goal | Key Question | Example | Models |
| Prediction | “What will happen?” | Accurately flagging spam emails. | Random Forest, GBM, SVM |
| Attribution | “Why does this happen?” | Identifying which ad campaign had a significant impact on sales. | Logistic/Linear Regression |
| Estimation | “What is the true relationship?” | Modeling the true dose-response curve of a new drug. | Logistic/Linear Regression |
2. The Bias-Variance Tradeoff
Bias (Underfitting): Error from a model being too simple and making incorrect assumptions.
Core Concepts and Definitions in Automata Theory
a) A DFA (Deterministic Finite Automaton) is a finite state machine where each state has exactly one transition for each input symbol. The transition table defines the state transitions for a given input, helping in automata implementation.B) DFA has a single transition per input, while NFA allows multiple transitions, including ε-moves.C) The ε-closure of a state is the set of states reachable from it using only ε-transitions.D) An ε-NFA is an NFA that includes ε-transitions, allowing movement
Read MoreDecoding Rising College Tuition: Structural Causes and Solutions
Understanding the Complexity of Rising College Tuition
The story of rising tuition is complex. Unfortunately, much of the public discussion about the cost of attendance is too simplistic. To understand the reasons for rising tuition, and the effect that this has on families, we need to break down the forces that affect how tuition is set and that determine who pays the bill.
Tuition Price vs. Actual Cost: Subsidies and Aid
Tuition is a price that rarely reflects the full cost of a year in college.
Read MoreUnderstanding Strings, Languages, and Automata in Computing
Understanding Character Strings
A character string, word, or phrase (often simply called a string) is an ordered sequence of elements of arbitrary, though finite, length, belonging to a certain alphabet. Generally, a character string is a sequence of letters, numbers, or other symbols. In usual mathematics, the letters w, x, y, z are often used to refer to strings. From a programming standpoint, a string can consist of any finite combination of characters from the available character set.
Defining
Read MoreMachine Learning Model Evaluation: Classification & Clustering Metrics
Classification Model Evaluation Metrics
Understanding how to evaluate classification models is crucial for assessing their effectiveness. This section details key metrics derived from the confusion matrix.
A. Confusion Matrix for Binary Classification
The Confusion Matrix is a fundamental tool for evaluating the performance of a classification model, especially for binary classification (Positive (+) and Negative (-)).
| Predicted + | Predicted – | |
|---|---|---|
| Actual + | TP (f++) | FN (f+-) |
| Actual – | FP (f-+) | TN (f–) |
Key Terms in
Read MoreStatistical Learning Quiz: Questions and Answers
1. Multiple Choice Questions (3 points each, only one correct answer)
(1) What is the primary goal of statistical learning?
✔ Answer: A. Estimating the relationship between input (X) and output (Y)
👉 Explanation: The goal of statistical learning is to understand how a set of predictor variables (\(X\)) relates to an outcome variable (\(Y\)). This helps in making predictions and drawing inferences about the data.
(2) Why do we estimate \( f \) in statistical learning?
✔ Answer: B. To improve