Chart assignment
Charts to read and discuss
Read each chart, then answer its questions. Every chart shows its source and date; open it for a table of the numbers and the data to download.
Chart 1 of 2 · Air travel
What causes most flight delays?
The interactive chart needs JavaScript. The numbers are on the chart's page.
In the 12 months through August 2026, 39.8% of all minutes of delay came from a late-arriving aircraft: a plane that left its last airport late. The airline itself (crew, maintenance, cleaning, fueling) caused 32.9%, the air traffic system 21.1% and severe weather 6%. Weather also hides in the other causes: BTS counts ordinary weather that slows traffic under the air traffic system.
Questions to discuss
- In one sentence of your own, what does this chart show?
- Find the biggest change or difference in the chart. What might explain it?
- Who collected these numbers, and how recent are they? What else would you want to know before drawing a conclusion?
Source: U.S. Bureau of Transportation Statistics, Airline On-Time Performance (Reporting Carrier On-Time Performance, 1987–present) (Public domain (U.S. government work)) · Data as of Aug 31, 2026
Open the chart and its numbersChart 2 of 2 · Income and poverty
What is the typical household income in each state?
The interactive chart needs JavaScript. The numbers are on the chart's page.
In the Census Bureau's 5-year survey ending in 2024, the typical household in District of Columbia earned $109,870 a year, the most, followed by Massachusetts ($103,960) and Maryland ($103,678). Mississippi was lowest at $56,447, and the U.S. median was $80,734. These are 5-year estimates in 2024 dollars, each with a margin of error.
How to read this chart
Each bar is the median household income in a state: half of households earn more and half earn less. The dashed line is the whole U.S., for comparison. These are survey estimates, and each has a margin of error: the true value is likely within that range, so states with overlapping ranges may not really differ.
Questions to discuss
- Find your state. Is it above or below the U.S. median, and by about how much?
- Why do statisticians often use the median instead of the average (mean) for income?
- Housing and groceries cost more in some states. What would you need to know to compare what these incomes can buy?
Source: U.S. Census Bureau, American Community Survey 5-year estimates (Public domain (U.S. government work). This product uses the Census Bureau Data API but is not endorsed or certified by the Census Bureau.) · Data as of Dec 31, 2024
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