DataX Practice Questions - CompTIA DataX (DY0-001) Exam - DataX Practice Questions

Question 1

A data scientist is selecting a loss function for a binary classification model where false negatives are 10x more costly than false positives (e.g., disease screening). Which loss function BEST addresses this class-cost imbalance?

Weighted binary cross-entropy assigning a higher penalty weight to false negatives Mean squared error (MSE) with standard uniform weighting Hinge loss used in support vector machines Categorical cross-entropy with softmax output activation

Correct Answer:

Weighted binary cross-entropy assigning a higher penalty weight to false negatives

Question 2

A data scientist observes that a gradient boosting model achieves 98% accuracy on training data but only 72% on held-out test data. Which regularization approach MOST directly addresses this overfitting?

Reducing the number of estimators, decreasing max tree depth, and increasing the subsample ratio and min_samples_leaf Increasing the learning rate to allow the model to converge faster on training data Adding more features from the training dataset to improve model expressiveness Switching to a simpler linear regression model to eliminate all overfitting

Correct Answer:

Reducing the number of estimators, decreasing max tree depth, and increasing the subsample ratio and min_samples_leaf

Question 3

Which statistical test is MOST appropriate for determining whether the means of three or more independent groups differ significantly?

One-way ANOVA (Analysis of Variance) followed by a post-hoc test (Tukey HSD) if the null hypothesis is rejected Student's t-test comparing each pair of groups independently Chi-square goodness-of-fit test comparing observed to expected frequencies Pearson correlation coefficient measuring linear association between two continuous variables

Correct Answer:

One-way ANOVA (Analysis of Variance) followed by a post-hoc test (Tukey HSD) if the null hypothesis is rejected

Question 4

A data scientist is building a recommendation system for an e-commerce platform. Which technique BEST handles the cold start problem for new users with no purchase history?

Content-based filtering using item attributes (category, price, description embeddings) combined with demographic-based popularity recommendations Collaborative filtering using matrix factorization on the user-item interaction matrix Deep learning recommendation model (DLRM) trained on all historical interaction data Association rules mining using Apriori algorithm on frequent itemsets from past transactions

Correct Answer:

Content-based filtering using item attributes (category, price, description embeddings) combined with demographic-based popularity recommendations

Question 5

What is the PRIMARY purpose of feature stores in an ML platform architecture?

Centralizing feature computation, storage, and serving so that training and inference use identical, consistently computed features without duplication Storing raw training datasets in a versioned data lake for experiment reproducibility Providing a visual interface for data scientists to explore feature distributions Automating hyperparameter search across multiple ML experiments

Correct Answer:

Centralizing feature computation, storage, and serving so that training and inference use identical, consistently computed features without duplication

Question 1

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Prepare with the DataX Practice Questions - CompTIA DataX (DY0-001) Exam practice quiz. This question bank includes 100 questions covering data, model, scientist, technique, and feature. Use it to review important concepts, identify knowledge gaps, and build confidence for the related exam, course, or assessment.

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DataX Practice Questions - CompTIA DataX (DY0-001) Exam

This practice set contains 100 questions from the matching question bank and focuses on data, model, scientist, technique, and feature. Work through each question carefully, review the provided solutions, and revisit topics that need more study before your next attempt.

This is an independent study resource intended for practice and review; it is not an official examination or an endorsement by any organization named in the title.

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DataX Practice Questions - CompTIA DataX (DY0-001) Exam

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