CodeHS Data-Driven Decision Making 2 — Questions and Answers
Question 1: A school wants to reduce its dropout rate. Which data source would BEST help identify at-risk students early?
- Student attendance records and grade trends (Correct answer)
- School building maintenance logs
- Teacher salary data
- School lunch menu preferences
Correct answer: Student attendance records and grade trends
Attendance records and grade trends are leading indicators that correlate strongly with dropout risk.
Question 2: When visualizing the relationship between two continuous numeric variables, which chart type is most appropriate?
- Pie chart
- Scatter plot (Correct answer)
- Stacked bar chart
- Histogram
Correct answer: Scatter plot
A scatter plot displays individual data points for two numeric variables, making it ideal for spotting correlations.
Question 3: A retailer notices sales spike every December. This pattern is best described as:
- Random variation
- A trend
- Seasonal variation (Correct answer)
- An outlier
Correct answer: Seasonal variation
Seasonal variation refers to regular, repeating fluctuations tied to a specific time of year.
Question 4: Which measure of central tendency is LEAST affected by extreme outliers in a dataset?
- Mean
- Median (Correct answer)
- Mode
- Range
Correct answer: Median
The median is the middle value and is resistant to the pull of very high or very low outliers.
Question 5: A company's data shows that ice cream sales and drowning incidents both increase in summer. This is an example of:
- Causation
- Spurious correlation (Correct answer)
- Negative correlation
- Statistical significance
Correct answer: Spurious correlation
Both variables are driven by a third factor (hot weather), making their correlation spurious rather than causal.
Question 6: In a database, which SQL clause is used to filter rows BEFORE grouping?
- HAVING
- ORDER BY
- WHERE (Correct answer)
- GROUP BY
Correct answer: WHERE
WHERE filters individual rows before any aggregation or grouping occurs, unlike HAVING which filters after grouping.
Question 7: A student surveys 30 classmates about study habits but wants to draw conclusions about all 500 students in the school. The 30 students represent the:
- Population
- Parameter
- Sample (Correct answer)
- Census
Correct answer: Sample
A sample is a subset of the larger population selected to represent the whole group for analysis.
CodeHS Data-Driven Decision Making 2
A school wants to reduce its dropout rate.
Which data source would BEST help identify at-risk students early?