CPA Data Analytics 3 — Questions and Answers
Question 1: What does ETL stand for in data analytics pipelines?
- Extract, Transfer, Load
- Extract, Transform, Load (Correct answer)
- Evaluate, Transform, Link
- Export, Translate, Load
Correct answer: Extract, Transform, Load
ETL stands for Extract, Transform, Load — the three-phase process of pulling data from sources, reshaping it, and loading it into a target system.
Question 2: A data analyst wants to identify which rows in a pandas DataFrame contain null values. Which method should they use?
- df.dropna()
- df.isnull() (Correct answer)
- df.fillna()
- df.notna()
Correct answer: df.isnull()
df.isnull() returns a boolean DataFrame of the same shape where True indicates a missing (null) value.
Question 3: In statistics, what does a p-value less than 0.05 typically indicate?
- The null hypothesis is definitively true
- The result is statistically significant at the 5% level (Correct answer)
- The effect size is large
- The sample size is too small
Correct answer: The result is statistically significant at the 5% level
A p-value < 0.05 means there is less than a 5% probability of observing the result (or more extreme) if the null hypothesis were true, so we reject it.
Question 4: Which SQL keyword is used to remove duplicate rows from a query result?
- UNIQUE
- DISTINCT (Correct answer)
- FILTER
- EXCEPT
Correct answer: DISTINCT
The DISTINCT keyword in a SELECT statement eliminates duplicate rows, returning only unique combinations of the selected columns.
Question 5: What type of data is represented by the Python list ['red', 'blue', 'green', 'red']?
- Continuous numerical data
- Ordinal data
- Nominal categorical data (Correct answer)
- Interval data
Correct answer: Nominal categorical data
Colors are nominal categorical data — they represent distinct categories with no inherent order or numerical meaning.
Question 6: In a box plot, what do the whiskers typically represent?
- The mean and standard deviation
- The minimum and maximum values only
- The range within 1.5 × IQR from the quartiles (Correct answer)
- The 10th and 90th percentiles
Correct answer: The range within 1.5 × IQR from the quartiles
By Tukey's convention, box plot whiskers extend to the farthest data point within 1.5 × IQR beyond Q1 and Q3; points beyond are plotted as outliers.
Question 7: Which technique splits a dataset into training and testing subsets to evaluate a predictive model's performance?
- Cross-tabulation
- Train-test split (Correct answer)
- Bootstrapping aggregation
- Stratified sampling
Correct answer: Train-test split
A train-test split reserves a portion of data (commonly 20-30%) as an unseen test set to measure how well a trained model generalizes.
CPA Data Analytics 3
What does ETL stand for in data analytics pipelines?