DMC Troubleshooting & Problem Resolution 2

Question 1

A classification model scores 99% accuracy on training data but 68% on the test set. What is the most likely problem?

Accepted Answer

Overfitting

Answer

Underfitting

Answer

Class imbalance only

Answer

Data leakage from the test set

Question 2

Which action is MOST appropriate to reduce overfitting in a decision tree?

Accepted Answer

Prune the tree or limit its depth

Answer

Increase the maximum tree depth

Answer

Remove the validation set

Answer

Add more irrelevant attributes

Question 3

A k-means run gives different clusters each time it is executed on the same data. What is the most likely cause?

Accepted Answer

Random centroid initialization

Answer

Missing values in the target

Answer

Too many records

Answer

The data is categorical

Question 4

A fraud detection model with only 1% positive cases predicts 'not fraud' for everything and reports 99% accuracy. What is the best fix to investigate first?

Accepted Answer

Address class imbalance and evaluate with precision/recall

Answer

Use accuracy as the only metric

Answer

Delete the minority class

Answer

Reduce the number of features to one

Question 5

Model performance drops sharply a few months after deployment even though the code has not changed. What is the most probable cause?

Accepted Answer

Concept or data drift

Answer

Hardware aging

Answer

A larger training set

Answer

Too many decimal places

Question 6

Which symptom most strongly suggests target leakage in a model?

Accepted Answer

Suspiciously near-perfect performance that collapses in production

Answer

Slow training time

Answer

Low variance across folds

Answer

Many missing values

Question 7

A linear regression shows a very high R² but coefficient signs that contradict domain knowledge. Which issue should be checked first?

Accepted Answer

Multicollinearity among predictors

Answer

Too few clusters

Answer

Insufficient epochs

Answer

Use of a test set

What Practice Test Geeks adds beyond an AI chat for DMC