DY0-001のPDF試験材料2026年最新の実際に出るDY0-001問題集
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質問 # 26
A data analyst wants to save a newly analyzed data set to a local storage option. The data set must meet the following requirements:
* Be minimal in size
* Have the ability to be ingested quickly
* Have the associated schema, including data types, stored with it
Which of the following file types is the best to use?
- A. JSON
- B. CSV
- C. Parquet
- D. XML
正解：C
解説：
Given the requirements:
* Minimized file size
* Fast ingestion
* Schema preservation (including data types)
The most appropriate format is:
# Parquet - It is a columnar storage file format developed for efficient data processing. Parquet files are compressed, support schema embedding, and enable fast columnar reads, making them ideal for analytical workloads and big data environments.
Why the other options are incorrect:
* A. JSON: Text-heavy and lacks native support for data types/schema.
* C. XML: Verbose and has poor performance in storage and ingestion speed.
* D. CSV: Flat structure, doesn't store data types or schema, and can be large in size.
Official References:
* CompTIA DataX (DY0-001) Official Study Guide - Section 6.2 (Data Storage Formats):"Parquet is a preferred format for data analysis as it provides efficient compression and encoding with embedded schema information, making it ideal for minimal storage and fast ingestion."
* Apache Parquet Documentation:"Parquet is designed for efficient data storage and retrieval. It includes schema support and works best for analytics use cases." Parquet is a columnar storage format that automatically includes schema (data types), uses efficient compression to minimize file size, and enables very fast reads for analytic workloads.
質問 # 27
A data scientist is working with a data set that has ten predictors and wants to use only the predictors that most influence the results. Which of the following models would be the best for the data scientist to use?
- A. OLS
- B. Ridge
- C. Weighted least squares
- D. LASSO
正解：D
解説：
# LASSO (Least Absolute Shrinkage and Selection Operator) regression performs both variable selection and regularization by adding an L1 penalty to the loss function. It shrinks less important feature coefficients to zero, effectively performing feature selection - perfect for identifying the most influential predictors.
Why the other options are incorrect:
* A: OLS uses all predictors and doesn't perform feature selection.
* B: Ridge regression applies an L2 penalty, shrinking coefficients but keeping all predictors.
* C: Weighted least squares adjusts for heteroscedasticity but doesn't reduce variable count.
Official References:
* CompTIA DataX (DY0-001) Study Guide - Section 3.3:"LASSO performs feature selection by zeroing out coefficients of less significant predictors."
* Statistical Learning Textbook, Chapter 6:"LASSO regression is ideal when model interpretability and variable reduction are important."
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質問 # 28
A computer vision model is trained to identify cats on a training set that is composed of both cat and dog images. The model predicts a picture of a cat is a dog. Which of the following describes this error?
- A. Sampling error
- B. Type II error
- C. Error due to reality
- D. False positive error
正解：B
解説：
# A Type II error occurs when the model fails to identify a positive instance - in this case, a cat. That is, it incorrectly classifies a cat (positive class) as a dog (negative class). This is also referred to as a false negative.
Why the other options are incorrect:
* A: "Error due to reality" is not a recognized statistical concept.
* B: A false positive would mean misclassifying a dog as a cat (opposite error).
* C: Sampling error refers to discrepancies between the sample and population, not a misclassification.
Official References:
* CompTIA DataX (DY0-001) Official Study Guide - Section 1.5:"Type II errors occur when a model incorrectly identifies a true positive as a negative - also known as a false negative."
* Pattern Recognition and Machine Learning, Chapter 9:"In binary classification, a Type II error means failing to detect a positive class instance, leading to a false negative result."
質問 # 29
In a modeling project, people evaluate phrases and provide reactions as the target variable for the model.
Which of the following best describes what this model is doing?
- A. Sentiment analysis
- B. TF-IDF vectorization
- C. Named-entity recognition
- D. Part-of-speech tagging
正解：A
解説：
# Sentiment analysis refers to using machine learning or NLP techniques to determine the sentiment or emotional tone behind a body of text (e.g., positive, neutral, or negative). When people provide reactions to phrases, the model is learning to associate language with subjective emotion or opinion.
Why the other options are incorrect:
* B: NER identifies entities (e.g., locations, organizations) - not emotions.
* C: TF-IDF is a feature engineering method, not a modeling goal.
* D: POS tagging classifies words by their grammatical function - not sentiment.
Official References:
* CompTIA DataX (DY0-001) Official Study Guide - Section 6.3:"Sentiment analysis models associate textual input with subjective labels, such as emotional response or polarity."
* Applied Text Analytics, Chapter 8:"When modeling user reactions to text, sentiment classification techniques are commonly employed."
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質問 # 30
A team is building a spam detection system. The team wants a probability-based identification method without complex, in-depth training from the historical data set. Which of the following methods would best serve this purpose?
- A. Logistic regression
- B. Naive Bayes
- C. Random forest
- D. Linear regression
正解：B
解説：
# Naive Bayes is a probabilistic classification algorithm based on Bayes' theorem. It is lightweight, fast, and effective for text-based classification problems like spam detection. It also performs well with small or simple training sets.
Why the other options are incorrect:
* A: Logistic regression is also probabilistic but requires more feature preprocessing.
* B: Random forest is accurate but computationally heavier.
* D: Linear regression is for continuous targets - not suitable for classification.
Official References:
* CompTIA DataX (DY0-001) Study Guide - Section 4.1:"Naive Bayes classifiers are ideal for spam detection and similar applications due to their efficiency and probabilistic nature."
* Text Classification Techniques, Chapter 4:"Naive Bayes requires minimal training and works well with high-dimensional, sparse data such as email content."
質問 # 31
Which of the following JOINS would generate the largest amount of data?
- A. CROSS JOIN
- B. LEFT JOIN
- C. RIGHT JOIN
- D. INNER JOIN
正解：A
解説：
# A CROSS JOIN returns the Cartesian product of the two tables - meaning every row from the first table is paired with every row from the second table. If Table A has m rows and Table B has n rows, a CROSS JOIN will return m × n rows, making it the largest possible result set of all JOIN types.
Why the other options are incorrect:
* A & B: RIGHT JOIN and LEFT JOIN return matched records plus unmatched rows from one side - but not all possible combinations.
* D: INNER JOIN returns only matched rows between tables, typically producing fewer records than a CROSS JOIN.
Official References:
* CompTIA DataX (DY0-001) Official Study Guide - Section 5.2:"CROSS JOINs generate the Cartesian product of two datasets and should be used carefully due to the exponential growth in the number of records."
* SQL for Data Scientists, Chapter 3:"CROSS JOINs can produce very large datasets, often unintentionally, due to their non-restrictive matching logic."
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質問 # 32
Which of the following modeling tools is appropriate for solving a scheduling problem?
- A. Gradient descent
- B. Decision tree
- C. Constrained optimization
- D. One-armed bandit
正解：C
解説：
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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質問 # 33
A data scientist needs to:
Build a predictive model that gives the likelihood that a car will get a flat tire.
Provide a data set of cars that had flat tires and cars that did not.
All the cars in the data set had sensors taking weekly measurements of tire pressure similar to the sensors that will be installed in the cars consumers drive.
Which of the following is the most immediate data concern?
- A. Insufficient domain expertise
- B. Lagged observations
- C. Granularity misalignment
- D. Multivariate outliers
正解：C
解説：
# Granularity misalignment refers to a mismatch between the level of detail in the predictor variables and the event being predicted.
In this case, flat tires are likely discrete, infrequent events, while tire pressure is measured weekly. If the prediction model is trying to link a specific tire pressure value to a binary outcome (flat tire: yes/no), and the timing doesn't align precisely, the predictor variable (pressure) may not be granular enough to accurately associate with the event.
Why the other options are incorrect:
* B: While outliers can exist, they are not the most immediate concern given the time-series nature of the data.
* C: While domain expertise is helpful, it doesn't directly address the data structure issue.
* D: Lagged observations can be engineered in modeling but aren't the primary problem here.
Official References:
* CompTIA DataX (DY0-001) Official Study Guide - Section 3.1 (Data Granularity):"Granularity misalignment occurs when the temporal or spatial resolution of features does not align with the prediction target."
* Data Science Process Guide, Section 2.3:"Predictive performance can suffer when temporal mismatch exists between observations and outcomes. Granularity issues must be resolved prior to modeling."
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質問 # 34
The most likely concern with a one-feature, machine-learning model is high error due to:
- A. dimensionality
- B. probability
- C. variance
- D. bias
正解：D
解説：
# A one-feature model is likely to be overly simplistic and may not capture the true complexity of the target variable. This leads to underfitting, which is associated with high bias - the model consistently misses the mark regardless of the data.
Why the other options are incorrect:
* B: High dimensionality is not a concern in this case - the model has too few features.
* C: Variance refers to overfitting - more common in overly complex models.
* D: Probability is a modeling technique, not a source of error.
Official References:
* CompTIA DataX (DY0-001) Official Study Guide - Section 4.2:"Models with insufficient features tend to underfit and exhibit high bias due to their inability to represent complex relationships."
* Bias-Variance Tradeoff - Data Science Textbook:"A high-bias model makes strong assumptions and is typically too simple to capture the underlying patterns in data."
質問 # 35
A data scientist uses a large data set to build multiple linear regression models to predict the likely market value of a real estate property. The selected new model has an RMSE of 995 on the holdout set and an adjusted R² of 0.75. The benchmark model has an RMSE of 1,000 on the holdout set. Which of the following is the best business statement regarding the new model?
- A. The model's adjusted R² is too low for the real estate industry.
- B. The model fails to improve meaningfully on the benchmark model.
- C. The model should be deployed because it has a lower RMSE.
- D. The model's adjusted R² is exceptionally strong for such a complex relationship.
正解：B
解説：
# The difference between the benchmark RMSE (1,000) and the new model RMSE (995) is minimal and may not justify replacing the existing model. Though the adjusted R² is decent, business decisions should be based on whether the improvement is statistically and practically significant.
Why the other options are incorrect:
* A: The RMSE improvement is marginal and may not be worth deployment effort.
* B: The adjusted R² of 0.75 is moderate, not necessarily "exceptionally strong."
* D: The claim about industry standards is unsupported and not universally true.
Official References:
* CompTIA DataX (DY0-001) Study Guide - Section 3.2:"Model selection must consider both statistical improvement and practical significance."
* Data Science Best Practices, Chapter 8:"Small improvements in performance metrics must be evaluated in the context of deployment cost and business impact."
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質問 # 36
A data scientist receives an update on a business case about a machine that has thousands of error codes. The data scientist creates the following summary statistics profile while reviewing the logs for each machine:
| Number of machines observed | 3,000,000
| Number of unique error codes observed | 19,000
| Median number of unique codes per machine | 7
| Median number of error transactions | 45
Which of the following is the most likely concern with respect to data design for model ingestion?
- A. Insufficient features
- B. Granularity misalignment
- C. Sparse matrix
- D. Multivariate outliers
正解：C
解説：
# 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."
質問 # 37
A data scientist has constructed a model that meets the minimum performance requirements specified in the proposal for a prediction project. The data scientist thinks the model's accuracy should be improved, but the proposed deadline is approaching. Which of the following actions should the data scientist take first?
- A. Request additional funding.
- B. Consult the key project stakeholder.
- C. Continue collecting data.
- D. Test additional model specifications.
正解：B
解説：
# 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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質問 # 38
A data scientist wants to digitize historical hard copies of documents. Which of the following is the best method for this task?
- A. Latent semantic analysis
- B. Optical character recognition
- C. Semantic segmentation
- D. Word2vec
正解：B
解説：
# Optical Character Recognition (OCR) is the process of converting scanned images or hard copy text into machine-encoded text. It is the standard technique for digitizing printed or handwritten content.
Why the other options are incorrect:
* A: Word2vec is for generating word embeddings from digital text.
* C: Latent Semantic Analysis analyzes semantic structure of existing digital documents.
* D: Semantic segmentation is used in image processing for pixel-wise classification - not text extraction.
Official References:
* CompTIA DataX (DY0-001) Official Study Guide - Section 6.3:"OCR converts scanned physical documents into text files that can be searched, analyzed, or stored digitally."
* Practical NLP Applications, Chapter 2:"OCR is a prerequisite for turning printed or written material into structured data suitable for text analytics."
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質問 # 39
A data scientist is analyzing a data set with categorical features and would like to make those features more useful when building a model. Which of the following data transformation techniques should the data scientist use? (Choose two.)
- A. Pivoting
- B. Scaling
- C. Linearization
- D. Normalization
- E. Label encoding
- F. One-hot encoding
正解：E、F
解説：
# Categorical variables must be transformed into numerical form for most machine learning models. Two standard approaches:
* One-hot encoding: Converts each category into a separate binary column (useful for nominal variables).
* Label encoding: Converts categories into integers (useful for ordinal or tree-based models).
Why other options are incorrect:
* A & E: Normalization and scaling are used for continuous variables, not categorical.
* C: Linearization refers to transforming relationships, not categorical conversion.
* F: Pivoting rearranges data structure but doesn't encode categories.
Official References:
* CompTIA DataX (DY0-001) Study Guide - Section 3.3:"Label encoding and one-hot encoding are common transformations applied to categorical variables to enable model compatibility."
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質問 # 40
Which of the following image data augmentation techniques allows a data scientist to increase the size of a data set?
- A. Scaling
- B. Clipping
- C. Cropping
- D. Masking
正解：C
解説：
# Cropping involves selecting portions of an image to create multiple training samples from one image. This technique helps increase dataset size and variability, which improves model generalization.
Why the other options are incorrect:
* A: Clipping typically refers to limiting pixel values, not augmentation.
* C: Masking hides or removes parts of an image - used more in object detection or inpainting, not to expand the dataset.
* D: Scaling changes the image size but doesn't create new samples.
Official References:
* CompTIA DataX (DY0-001) Study Guide - Section 6.3:"Cropping is a data augmentation strategy that allows for synthetic expansion of the dataset by generating multiple views."
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質問 # 41
A data scientist is performing a linear regression and wants to construct a model that explains the most variation in the data. Which of the following should the data scientist maximize when evaluating the regression performance metrics?
- A. R²
- B. AUC
- C. p value
- D. Accuracy
正解：A
解説：
# R² (coefficient of determination) quantifies how much of the variance in the dependent variable is explained by the model. A higher R² means a better fit to the data, making it the metric to maximize for explanatory power in regression analysis.
Why the other options are incorrect:
* A: Accuracy is used in classification, not regression.
* C: p-values test statistical significance of coefficients, not overall model fit.
* D: AUC (Area Under the Curve) applies to classification models, not regression.
Official References:
* CompTIA DataX (DY0-001) Study Guide - Section 3.2:"R² is a regression performance metric indicating the proportion of variance explained by the independent variables."
質問 # 42
During EDA, a data scientist wants to look for patterns, such as linearity, in the data. Which of the following plots should the data scientist use?
- A. Scatter
- B. Q-Q
- C. Violin
- D. Box-and-whisker
正解：A
解説：
# Scatter plots are used to examine relationships and trends between two numeric variables. They are especially effective at revealing linear (or nonlinear) patterns, clusters, and outliers.
Why the other options are incorrect:
* A: Violin plots show distribution and density, not relationships.
* B: Box plots compare distributions across groups but don't reveal linearity.
* D: Q-Q plots test normality, not variable relationships.
Official References:
* CompTIA DataX (DY0-001) Official Study Guide - Section 1.2:"Scatter plots are commonly used during EDA to identify correlations, linearity, and outliers between two continuous variables."
* Data Science Fundamentals, Chapter 2 - EDA Techniques:"To assess linear trends and relationships, scatter plots provide a direct visual assessment between variables."
質問 # 43
A data scientist needs to determine whether product sales are impacted by other contributing factors. The client has provided the data scientist with sales and other variables in the data set.
The data scientist decides to test potential models that include other information.
INSTRUCTIONS
Part 1
Use the information provided in the table to select the appropriate regression model.
Part 2
Review the summary output and variable table to determine which variable is statistically significant.
If at any time you would like to bring back the initial state of the simulation, please click the Reset All button.
正解：
解説：
See explanation below.
Explanation:
Part 1
Linear regression.
Of the four models, linear regression has the highest R² (0.8), indicating it explains the greatest proportion of variance in sales.
Part 2
Var 4 - Net operations cost.
Net operations cost has a p-value of essentially 0 (far below 0.05), indicating it is the only additional predictor statistically significant in explaining sales. Neither inventory cost (p#0.90) nor initial investment (p#0.23) reach significance.
質問 # 44
A movie production company would like to find the actors appearing in its top movies using data from the tables below. The resulting data must show all movies in Table 1, enriched with actors listed in Table 2.
Which of the following query operations achieves the desired data set?
- A. Perform an INTERSECT between Table 1 using column Movie, and Table 2 using column Acted_In.
- B. Perform a LEFT JOIN on Table 1 using column Movie, with Table 2 using column Acted_In.
- C. Perform a UNION between Table 1 using column Movie, and Table 2 using column Acted_In.
- D. Perform an INNER JOIN between Table 1 using column Movie, and Table 2 using column Acted_In.
正解：B
解説：
# A LEFT JOIN ensures all rows from Table 1 (Top Movies) are preserved, even if there's no matching actor data in Table 2. This matches the requirement to show all movies, enriched with actor information when available.
Why the other options are incorrect:
* A: INNER JOIN would exclude movies without matching actor entries.
* B: UNION combines distinct rows - not appropriate for matching columns between two tables.
* C: INTERSECT shows only common movies - excludes unmatched top movies.
Official References:
* CompTIA DataX (DY0-001) Study Guide - Section 5.2:"LEFT JOINs are used when all records from one table (primary) must be retained, even if there are no matching rows in the secondary table."
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質問 # 45
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