DA0-002 Practice Exam 57 — 20 Questions

Question 1

In time series decomposition, a pattern that repeats at regular intervals (e.g., weekly, yearly) is called:

Accepted Answer

Seasonality. Seasonality refers to regular, periodic patterns in time series data.

Answer

Cyclical

Answer

Irregular

Answer

Trend

Question 2

A dataset contains a feature 'Age' with values ranging from 18 to 95. To prepare data for a k-nearest neighbors algorithm, which transformation should be applied to 'Age'?

Accepted Answer

Min-max normalization. Min-max normalization scales features to a fixed range (e.g., 0-1), which is appropriate for distance-based algorithms like k-NN.

Answer

Z-score standardization

Answer

No transformation needed

Answer

Log transformation

Question 3

A data analyst has a time series of monthly sales data. They observe that sales are consistently higher every December and lower every January. Which component of time series does this pattern represent?

Accepted Answer

Seasonality. Regular patterns that repeat within one year are seasonality.

Answer

Irregular

Answer

Cyclical

Answer

Trend

Question 4

An organization needs to store raw data from IoT sensors in its native format for future analysis. Which storage solution is best suited for this purpose?

Accepted Answer

Data lake. A data lake is designed to store raw data in its native format, including unstructured and semi-structured data from IoT sensors, without requiring a predefined schema. This allows the organization to preserve the original data for future analysis, unlike traditional databases that enforce structure upon ingestion.

Answer

Relational database

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Data mart

Answer

Data warehouse

Question 5

A stock analyst is analyzing monthly sales data for a retail company and observes a consistent pattern of high sales every December. This pattern is most likely an example of which time series component?

Accepted Answer

Seasonality. Seasonality refers to regular, predictable patterns that repeat at fixed intervals (e.g., yearly, monthly). The consistent December peak indicates a seasonal pattern.

Answer

Irregular

Answer

Cyclical

Answer

Trend

Question 6

In simple linear regression, the coefficient of determination R² measures:

Accepted Answer

The proportion of variance in the dependent variable explained by the independent variable. R² indicates the proportion of variance in the dependent variable explained by the independent variable.

Answer

The probability that the slope is zero

Answer

The slope of the regression line

Answer

The strength and direction of the linear relationship

Question 7

A data analyst is evaluating data quality issues in a customer database. Which TWO actions are best practices for ensuring data consistency?

Accepted Answer

Standardizing date formats across all tables. Standardizing date formats across all tables (Option B) ensures that date values are stored and interpreted uniformly, eliminating inconsistencies that arise from mixed formats (e.g., MM/DD/YYYY vs. DD-MM-YY). This practice directly supports data consistency by enforcing a single representation, which is critical for accurate querying, reporting, and integration across systems.

Answer

Allowing null values for foreign keys

Answer

Enabling cascading updates on primary keys

Answer

Using data profiling to identify duplicate records

Question 8

A retail company wants to segment its customers based on purchase history. Which THREE methods are appropriate for customer segmentation?

Accepted Answer

RFM analysis. K-means clustering, hierarchical clustering, and RFM analysis are common segmentation techniques. Linear regression and t-test are not segmentation methods.

Answer

Linear regression

Answer

t-test

Question 9

A data analyst is cleaning a dataset with missing values in a time series of daily temperatures. The missing values occur sporadically. Which imputation method is most appropriate to maintain the temporal trend?

Accepted Answer

Interpolation. Interpolation estimates missing values by using surrounding data points and is suitable for time series with a trend. Forward-fill carries the last observation forward, which may not capture trend well. Mean imputation ignores order.

Answer

Forward-fill

Answer

Mean imputation

Answer

Median imputation

Question 10

A data analyst creates a report and wants to ensure it tells a compelling story. Which element is most important for data storytelling?

Accepted Answer

Using a narrative arc with context.. Data storytelling relies on a narrative arc—introducing context, building tension through data insights, and resolving with actionable conclusions—to engage the audience and make the data memorable. Without a narrative, even the most accurate data fails to drive understanding or decision-making. This aligns with the DA0-001 objective of communicating data insights effectively.

Answer

Using only one chart type for consistency.

Answer

Avoiding any visual elements to keep focus on text.

Answer

Including all data without filtering.

Question 11

A data analyst is summarizing the central tendency of a dataset with extreme outliers. Which measure is most robust to outliers?

Accepted Answer

Median. The median is not affected by extreme values, unlike the mean.

Answer

Standard deviation

Answer

Mean

Answer

Range

Question 12

A data scientist is building a model to predict customer churn (yes/no). After training a logistic regression model, the coefficient for 'monthly charges' is 0.05 with a p-value of 0.03. Which interpretation is correct at α=0.05?

Accepted Answer

For every unit increase in monthly charges, the odds of churn increase by about 5%.. The p-value < 0.05 indicates a statistically significant relationship; the positive coefficient means higher charges increase the log-odds of churn.

Answer

The model's R-squared is 0.05.

Answer

Monthly charges decrease the probability of churn.

Answer

Monthly charges have no significant effect on churn.

Question 13

A data analyst calculates the mean, median, and mode of a sales dataset and finds they are all equal. Which type of distribution does this indicate?

Accepted Answer

Normal distribution. When mean, median, and mode are equal, the distribution is symmetric and typically bell-shaped (normal).

Answer

Skewed right

Answer

Bimodal distribution

Answer

Skewed left

Question 14

A data analyst needs to present the results of a customer segmentation analysis to the marketing team. The analysis identified four segments based on purchasing behavior. Which visualization is most effective for showing the characteristics of each segment?

Accepted Answer

Radar chart. A radar chart is the most effective visualization for comparing multiple quantitative variables across different categories, such as the purchasing behavior characteristics of each customer segment. It allows the marketing team to see the profile of each segment at a glance by plotting each characteristic on a separate axis radiating from a central point, making it easy to identify strengths, weaknesses, and similarities between segments.

Answer

Histogram

Answer

Heatmap

Answer

Scatter plot

Question 15

Which TWO of the following are components of time series data?

Accepted Answer

Trend. Trend and seasonality are classic components of time series. Mean, median, and variance are statistical measures but not components of time series decomposition.

Answer

Mean

Answer

Variance

Answer

Median

Question 16

A logistic regression model predicts customer churn (0=no churn, 1=churn). The model outputs probabilities. Which THREE of the following statements about logistic regression are correct?

Accepted Answer

The model output is a probability between 0 and 1.. Logistic regression outputs probabilities; it uses the logistic function (sigmoid) to map linear combination to [0,1]. The coefficients represent log-odds changes. R² is for linear regression; pseudo-R² is used but not standard R².

Answer

The coefficient of determination R² is used to assess model fit.

Answer

The model uses the linear regression equation y = mx + b directly.

Question 17

A company is planning an A/B test to compare two website designs. Which THREE of the following must be determined before the test begins to ensure valid results? (Select three.)

Accepted Answer

The desired effect size. Sample size (based on power and effect size), significance level (α), and desired effect size are all pre-specified to design the test. The p-value is an outcome, not a pre-test parameter. The hypothesis is defined beforehand, but which one is false? Actually null and alternative hypotheses should be pre-specified, but the phrasing 'which one is true' is not determined before; the test determines that. So correct are: determine minimum sample size, determine significance level, and determine desired effect size.

Answer

The p-value of the test

Answer

Which hypothesis is true

Question 18

A data analyst is reviewing a dataset containing house prices. The mean price is $350,000 and the median is $280,000. Which of the following best describes the distribution of house prices?

Accepted Answer

The distribution is right-skewed.. When the mean is greater than the median, the distribution is right-skewed (positively skewed) because higher values pull the mean upward.

Answer

The distribution is symmetric.

Answer

The distribution is left-skewed.

Answer

The distribution is bimodal.

Question 19

An analyst wants to compare the average sales revenue across three different store locations. Which TWO statistical methods are appropriate for this comparison?

Accepted Answer

ANOVA. ANOVA compares means of three or more groups. A t-test compares only two groups. Chi-square tests categorical independence. Correlation measures linear relationship. Descriptive stats summarise but don't compare multiple groups inferentially.

Answer

Two-sample t-test

Answer

Descriptive statistics

Answer

Chi-square test

Question 20

A data analyst wants to segment customers based on purchasing behavior such as frequency, monetary value, and recency. Which TWO clustering evaluation methods can help determine the optimal number of clusters? (Select two.)

Accepted Answer

Silhouette score. The elbow method uses within-cluster sum of squares, and the silhouette score measures cohesion and separation. Both help choose k. Correlation coefficient is for association, not clustering. ANOVA and t-test are for hypothesis testing.

Answer

Correlation coefficient

Answer

ANOVA

Answer

t-test