Ready-made assignment · AP statistics

AP Statistics chart assignment

Six charts of real public data for AP Statistics topics: least-squares trend lines, margins of error, sampling bias, proportions, association and exponential patterns.

  1. How much has the US warmed since 1895?
  2. What share of people live in poverty in each state?
  3. How much do students from your college earn 10 years later?
  4. How often do NFL home teams win?
  5. How often are NFL field goals good from each distance?
  6. How much rarer is each step up in earthquake magnitude?

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Chart 1 of 6 · Climate

How much has the US warmed since 1895?

The interactive chart needs JavaScript. The numbers are on the chart's page.

The contiguous US averaged 54.6°F in 2025. The warmest year since records began in 1895 was 2024, at 55.5°F. Through 2025, the dashed trend line, the straight line that best fits every year, rose about 0.18°F a decade, or 2.3°F since 1895, and warming had sped up to about 0.5°F a decade since 1970. Alaska and Hawaii aren't included.

How to read this chart

Each point is one year's average temperature across the lower 48 states, in degrees Fahrenheit. The axis doesn't start at zero, so a small rise looks steep: read the numbers on the axis, not the height of the line. The dashed line is the trend, the straight line that best fits every year; single years bounce above and below it.

Questions to discuss

  1. The dashed line is the least-squares regression line. About how many degrees per decade does its slope rise?
  2. Single years scatter above and below the line. What does that scatter (the residuals) tell you about any one year?
  3. Warming sped up after 1970. Why might one straight line fitted to every year since 1895 understate recent change?

Source: NOAA National Centers for Environmental Information, Climate at a Glance (Public domain (U.S. government work)) · Data as of Dec 31, 2025

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Chart 2 of 6 · Income and poverty

What share of people live in poverty in each state?

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In the Census Bureau's five-year survey ending in 2024, 12.5% of people in the U.S. lived below the official poverty line. Louisiana (18.9%) and Mississippi (18.9%) had the highest rates, and New Hampshire the lowest, 7.2%. The official poverty line is the same across the country, so it doesn't reflect higher living costs in some states.

Questions to discuss

  1. Which states have the highest and lowest poverty rates, and what is each state's margin of error?
  2. Two states have the same rate. If their margins of error overlap, can you say one has more poverty than the other?
  3. The figures come from a survey of a sample of households. Why do smaller states tend to have wider margins of error?

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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Chart 3 of 6 · College

How much do students from your college earn 10 years later?

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Search 1,782 colleges that mainly award bachelor's degrees. Ten years after starting, former students of Ohio State earned a median of $67,080 a year, and those of California Institute of Technology, CA, the highest, $166,642. Earnings cover only students who received federal aid (grants or loans), whether or not they graduated, and who were working and not in school. They describe students who started about ten years before, with earnings in the two years through 2023, adjusted for inflation.

Questions to discuss

  1. Find a college you know. What is the median earnings of its students 10 years after they started?
  2. Earnings cover only students who received federal aid and were working. How could leaving out the others bias the median?
  3. Can this chart show that a college causes its students to earn more? What else could explain the differences?

Source: U.S. Department of Education, College Scorecard (Public domain (U.S. government work)) · Data as of Dec 31, 2023

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Chart 4 of 6 · NFL

How often do NFL home teams win?

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Home teams won 53.8% of NFL regular-season games in 2025; from 1999 to 2018 they usually won 55% to 60%. In 2020, played mostly without fans, it fell to 50.4%, barely better than a coin flip. A tie counts as half a win; games at neutral sites, such as those abroad, are left out. The chart starts in 1999, the first season in nflverse's data.

Questions to discuss

  1. In a typical season from 1999 to 2018, what proportion of games did home teams win?
  2. In 2020 games were played mostly without fans and the proportion fell to about 50%. Is that strong evidence that crowds help home teams, or could it be chance?
  3. A season has about 270 games. Roughly how far from 50% could the proportion land by chance alone if home field didn't matter?

Source: nflverse, NFL schedules and scores (nflverse-data) (CC BY 4.0 (nflverse)) · Data as of Jan 4, 2026

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Chart 5 of 6 · NFL

How often are NFL field goals good from each distance?

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In the NFL regular season that ended in January 2026, kickers made 98.1% of field goal tries from under 30 yards, 84.3% from 40 to 49 yards and 68.8% from 50 yards or longer. Blocked kicks count as misses.

Questions to discuss

  1. What proportion of field goals are made from under 30 yards, and from 50 yards or longer?
  2. Describe the association between distance and success. Is it positive or negative, and is it straight or curved?
  3. Distance is grouped into ranges here. What would you gain or lose by plotting every kick's exact distance instead?

Source: nflverse, NFL team season stats (nflverse-data) (CC BY 4.0 (nflverse)) · Data as of Jan 4, 2026

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Chart 6 of 6 · Earthquakes

How much rarer is each step up in earthquake magnitude?

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In 2025 the world recorded 6,428 earthquakes of magnitude 4.5 to 4.9, 1,983 of magnitude 5, 129 of magnitude 6, 15 of magnitude 7 and 1 of magnitude 8 or more. Each step up in magnitude is roughly ten times rarer, and releases about 32 times more energy. Countless smaller quakes go unrecorded worldwide, so the chart starts at 4.5.

How to read this chart

Each bar counts the earthquakes recorded worldwide in one year within a range of magnitudes. The bars start at zero. Each whole step up in magnitude releases about 32 times more energy, so a magnitude 7 quake is far more than one step stronger than a 6.

Questions to discuss

  1. About how many times more earthquakes are there in each magnitude band than in the band above it?
  2. The counts fall by roughly the same factor each step. What kind of model fits that pattern, linear or exponential?
  3. If you took the logarithm of each count, what shape would you expect the graph to have, and why does that help?

Source: U.S. Geological Survey, ANSS Comprehensive Earthquake Catalog (ComCat) (Public domain (U.S. government work); source U.S. Geological Survey) · Data as of Dec 31, 2025

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A chart for class, every Monday

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