MLS-C01 Modeling Practice Question
A company uses a linear regression model to predict house prices. The model's R-squared is 0.95 on the training set but 0.60 on the test set. Which of the following is the most likely cause?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Overfitting
Such a large gap between training and test R-squared indicates overfitting. Option B is wrong because if the model were underfitting, both would be low. Option C is wrong because multicollinearity affects both training and test sets similarly and does not typically cause such a gap. Option D is wrong because data leakage would likely cause high test R-squared, not a significant drop.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Overfitting
Why this is correct
Correct. A high training R-squared with a much lower test R-squared is a classic sign of overfitting, where the model learns noise in the training data but fails to generalize.
- ✗
Underfitting
Why it's wrong here
Incorrect. Underfitting would result in low R-squared on both training and test sets, not a large gap.
- ✗
Multicollinearity among features
Why it's wrong here
Incorrect. Multicollinearity among features affects the stability of coefficient estimates but generally impacts training and test performance similarly and does not create such a large discrepancy.
- ✗
Data leakage
Why it's wrong here
Incorrect. Data leakage typically leads to overly optimistic test performance, i.e., high test R-squared, not a significant drop relative to training.
Go deeper
Related to this question
About these practice questions
One of 1,672 original MLS-C01 practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. Learn why practice questions differ from exam dumps →
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This MLS-C01 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the MLS-C01 exam.