A data analyst is creating a dashboard to monitor server CPU utilization over the past 24 hours. Which chart type is most appropriate for showing the trend of CPU usage over time?
Trap 1: Scatter plot
A scatter plot encodes two continuous variables as x and y positions to reveal correlation, so it cannot place CPU percentage against a sequential time axis. It is tempting for plotting many readings, but a line chart is the correct choice when the x-axis is a continuous time interval showing trend.
Trap 2: Pie chart
A pie chart encodes each category as an angular slice of a single whole, so it cannot represent 24 sequential hourly CPU readings or their trend. It is tempting for showing proportions of total capacity, but a line chart is correct when the x-axis is continuous time.
Trap 3: Bar chart
Vertical bars encode discrete categorical magnitudes, so plotting 24 hourly readings produces separate columns rather than a continuous trend line. It is tempting because bars show magnitude clearly, but a line chart is correct when the x-axis is a continuous time interval.
- A
Scatter plot
Why it fails: A scatter plot encodes two continuous variables as x and y positions to reveal correlation, so it cannot place CPU percentage against a sequential time axis. It is tempting for plotting many readings, but a line chart is the correct choice when the x-axis is a continuous time interval showing trend.
- B
Pie chart
Why it fails: A pie chart encodes each category as an angular slice of a single whole, so it cannot represent 24 sequential hourly CPU readings or their trend. It is tempting for showing proportions of total capacity, but a line chart is correct when the x-axis is continuous time.
- C
Line chart
A line chart plots continuous data points connected by segments, with time on the horizontal axis and CPU percentage on the vertical axis. This directly satisfies the stem's requirement to show a trend across the past 24 hours, revealing peaks, troughs and sustained patterns that categorical charts cannot express.
- D
Bar chart
Why it fails: Vertical bars encode discrete categorical magnitudes, so plotting 24 hourly readings produces separate columns rather than a continuous trend line. It is tempting because bars show magnitude clearly, but a line chart is correct when the x-axis is a continuous time interval.