CompTIA DY0-001 - CompTIA DataX Exam

→ Occam’s razor is a principle that suggests selecting the simplest solution that sufficiently explains the data. In data science, this translates to favoring simpler models (fewer features) when performance is similar.

Therefore, the model with the fewest features and the highest performance is preferred — balancing simplicity and effectiveness.

Why the other options are incorrect:

B: Poor performance undermines utility.

C & D: More features add complexity and risk overfitting, making them less desirable when simpler models suffice.

Official References:

CompTIA DataX (DY0-001) Official Study Guide – Section 3.2:“Simplicity in models improves interpretability and robustness. When models perform similarly, the simpler model should be preferred.”

Data Science Principles, Chapter 5:“Occam's razor encourages the use of fewer features to minimize complexity while preserving accuracy.”

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→ For executive-level presentations, the focus should be on strategic outcomes. Therefore, concise results, clear actionable recommendations, visual summaries (charts), and minimal justifications are best. Technical details such as p-values, code, or full methods are too granular.

Why the other options are incorrect:

A: Too method-heavy for executive audiences.

C: Includes code reviews — not suitable for a CEO.

D: Overly technical for high-level stakeholders.

Official References:

CompTIA DataX (DY0-001) Study Guide – Section 5.5:“Executive communication should focus on outcome-driven recommendations, high-level insights, and actionable visuals.”

Harvard Business Review – Communicating Data to Executives:“Avoid technical detail. Use visuals and clearly stated recommendations supported by business-focused justifications.”

→ With 19,000 unique error codes and only 7 codes per machine (on median), the data structure will likely consist of a very large number of binary features (e.g., one-hot encoded error codes), most of which will be 0 for any given machine. This leads to a sparse matrix—where the majority of elements are zero—which poses computational and modeling challenges.

Why the other options are incorrect:

B: Granularity misalignment would mean mismatched levels (e.g., mixing daily and hourly data), which is not the issue here.

C: There are many features (error codes), not too few.

D: Multivariate outliers involve unusual combinations across features, not sparsity.

Official References:

CompTIA DataX (DY0-001) Study Guide – Section 3.3:“High-cardinality categorical features can result in sparse matrices, especially when one-hot encoded for models.”

→ Decision trees are supervised classification models that can be used to predict a categorical target variable (e.g., Habitat: Land or Sea) based on input features (e.g., Wrapper color, Wrapper shape, Animal type). They are interpretable, require minimal preprocessing, and are ideal for structured categorical data like this.

Why the other options are incorrect:

A: ARIMA (AutoRegressive Integrated Moving Average) is used for time-series forecasting, not classification.

B: Linear regression is used for predicting continuous numeric values, not categorical variables like "Land" or "Sea".

C: Association rules (like in market basket analysis) are used to discover relationships or co-occurrence among variables, not to build predictive models.

Official References:

CompTIA DataX (DY0-001) Study Guide – Section 4.1 & 4.2:“Decision trees are powerful classifiers for categorical output variables and allow for interpretable models based on feature splits.”

Machine Learning Textbook, Chapter 6:“Decision trees are ideal for early-stage model prototyping when the output is categorical and the data structure is tabular.”

Scheduling problems typically involve the assignment of limited resources (e.g., time, personnel, machines) over time to tasks, often under constraints. These problems are inherently mathematical and are typically solved using:

→ Constrained Optimization – which is a mathematical technique for optimizing an objective function subject to one or more constraints. This tool is widely used for operations research problems such as scheduling, resource allocation, logistics, and supply chain optimization.

Why the other options are incorrect:

A. One-armed bandit: Refers to a class of algorithms used for balancing exploration and exploitation, not scheduling.

C. Decision tree: Used for classification and regression, not for constraint-based scheduling.

D. Gradient descent: An optimization method for training models (typically ML), but not specifically suitable for complex constraint-based scheduling.

Official References:

CompTIA DataX (DY0-001) Official Study Guide – Section 3.4 (Modeling Tools):“Scheduling and allocation problems are best addressed using constrained optimization techniques which allow incorporation of resource limits and goal functions.”

Data Science and Operations Research Foundations, Chapter 7:“Constraint-based optimization is the primary mathematical strategy used in scheduling problems to meet deadlines, minimize cost, or maximize throughput.”

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→ A systematic error is a consistent, repeatable error caused by faulty equipment or flawed measurement techniques. Since one sensor consistently over-reports values, this is a classic case of systematic error.

Why the other options are incorrect:

A: Synthetic data is artificially generated — unrelated to sensor malfunction.

C: Heteroskedasticity refers to non-constant variance — not consistent bias.

D: Idiosyncratic errors are random and unpredictable — not consistent.

Official References:

CompTIA DataX (DY0-001) Study Guide – Section 1.4:“Systematic errors arise from consistent biases in measurement devices or methods, requiring calibration or correction.”

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→ The model already meets the performance goals outlined in the project proposal. However, since the deadline is near and the data scientist is considering further improvements, the correct approach is to:

→ Consult the key project stakeholder. This ensures transparency and aligns actions with stakeholder priorities — whether to proceed with deployment or invest in further model tuning.

Why the other options are incorrect:

A: Collecting more data requires time and may exceed project scope.

B: Requesting funding is premature and not justified if performance goals are already met.

D: Testing new models takes time and may delay delivery — stakeholder input is needed first.

Official References:

CompTIA DataX (DY0-001) Study Guide – Section 5.1:“Stakeholder engagement is critical in project decision-making, especially when trade-offs exist between quality and timelines.”

CRISP-DM Framework – Evaluation Phase:“Before modifying models that meet objectives, it is essential to consult business stakeholders to align with their expectations.”

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→ Multicollinearity occurs when independent variables are highly correlated with each other. This can distort coefficient estimates and reduce model interpretability. A correlation matrix is the primary tool used to detect it.

Why the other options are incorrect:

A & C: Under/oversampling relate to class imbalance, not variable correlation.

D: Overfitting is related to model complexity, not directly observable via a correlation matrix.

Official References:

CompTIA DataX (DY0-001) Study Guide – Section 3.2:“Correlation matrices are used to detect multicollinearity — high correlations among predictors that may destabilize models.”

→ The Traveling Salesman Problem (TSP) is a classic example of a constrained optimization problem. The goal is to find the shortest possible route that visits a set of locations once and returns to the origin point — under constraints such as distance, order, and time.

Why the other options are incorrect:

A: The cold start problem is related to recommender systems, not optimization.

C: Calculating a local maximum is part of optimization but not necessarily constrained.

D: Gradient descent is an optimization method, but not itself a problem with constraints.

Official References:

CompTIA DataX (DY0-001) Official Study Guide – Section 3.4:“Constrained optimization involves solving problems under defined limitations — e.g., distance or time constraints in routing.”

Optimization Techniques in Data Science, Chapter 6:“TSP is a benchmark in combinatorial optimization, representing a multi-variable problem with strict constraints.”

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