DAC Fundamentals of Data Analytics 3 — Questions and Answers
Question 1: What is a 'null value' in a dataset?
- A value equal to zero
- A missing or unknown value (Correct answer)
- A negative number
- A duplicate entry
Correct answer: A missing or unknown value
A null represents missing or unknown data, which is distinct from zero.
Question 2: Which sampling method gives every member of a population an equal chance of selection?
- Convenience sampling
- Random sampling (Correct answer)
- Snowball sampling
- Quota sampling
Correct answer: Random sampling
Random sampling ensures each member has an equal probability of being chosen.
Question 3: A correlation coefficient of -0.9 indicates:
- A strong positive relationship
- No relationship
- A strong negative relationship (Correct answer)
- A weak negative relationship
Correct answer: A strong negative relationship
A value near -1 indicates a strong inverse relationship between variables.
Question 4: What does 'ETL' stand for in data processing?
- Extract, Transform, Load (Correct answer)
- Evaluate, Test, Launch
- Enter, Track, Log
- Export, Trim, Link
Correct answer: Extract, Transform, Load
ETL means Extract, Transform, Load — the process of moving data into a warehouse.
Question 5: Which data type would 'customer satisfaction rated 1 to 5' represent?
- Nominal
- Ordinal (Correct answer)
- Ratio
- Interval
Correct answer: Ordinal
Ordinal data has a meaningful order but no consistent interval between ranks.
Question 6: The purpose of a data dictionary is to:
- Store the actual records
- Define fields, types, and meanings of data (Correct answer)
- Encrypt the database
- Generate charts automatically
Correct answer: Define fields, types, and meanings of data
A data dictionary documents field names, data types, and their meanings.
Question 7: Which visualization best reveals the relationship between two continuous variables?
- Bar chart
- Scatter plot (Correct answer)
- Pie chart
- Table
Correct answer: Scatter plot
A scatter plot plots two continuous variables to reveal correlation or patterns.
DAC Fundamentals of Data Analytics 3
What is a 'null value' in a dataset?