Why this matters on the SAT
A data question gives you a short text with a graph or a table, then asks which choice most effectively uses data from the graph to complete a statement, or which best describes data that support a claim. The two stems come up about equally. About a third of Command of Evidence questions come with a graph or a table, about half of them with a bar graph.
The graphic usually holds more numbers than the question needs, so the question really asks: which numbers does the sentence need, and does the choice report them right?
SAT example
A student is writing a report about how quickly riders adopted mobile ticketing in several public transportation systems. The student claims that the percentage of riders using mobile tickets on MetroRail in 2018 was _____
Which choice most effectively uses data from the graph to complete the statement?
lower than on the city bus system but higher than on the ferry system, and in 2023 was about the same as on the city bus system.
higher than on the city bus system, and in 2023 was higher than on both the city bus system and the ferry system.
higher than on both the city bus system and the ferry system, and in 2023 was lower than on the city bus system but higher than on the ferry system.
about the same as on the city bus system, and in 2023 was lower than on the ferry system but higher than on the city bus system.
Solution to the example
The blank needs: how MetroRail compared with the bus and the ferry in 2018 and, as every choice adds, in 2023.
The graph: three bars a year; MetroRail is the middle one.
Predict: in 2018, MetroRail's 20% beat the bus (15%) and the ferry (10%). In 2023, its 50% trailed the bus (55%) but beat the ferry (35%).
Cross out: A puts MetroRail below the bus in 2018, and D puts it below the ferry in 2023.
Check: C has both years right, so the answer is C.
B tempts most: its 2018 half is right, but in 2023 MetroRail trails the bus.
Data questions take one routine, whatever the stem:
Step 1 comes before the graphic because the sentence with the blank, or the claim, tells you which of its numbers count. Much of the text before it is background, except a line that says what a number measures or which group is which. Here's a short table of our own:
The school library
Graphic Novel Checkouts at a School Library
| Month | Front shelf | Back room |
|---|---|---|
| September | 40 | 35 |
| October | 55 | 20 |
| November | 70 | 30 |
A school library put half its graphic novels on a shelf by the front door and left the rest in the back room. The front shelf had 15 more checkouts in October than in _____
The sentence also says which way to count. October had 55, so the blank needs the month with 15 fewer:
November is 15 away from October too, but it's 15 above it, so that sentence runs the wrong way: turned around. Before you look up a single number, say which way the comparison runs.
Which month fills the blank? The back room had 10 more checkouts in November than in _____
In this question, the sentence sets one trail against another. Work out the length the blank needs, then find it on the graph.
Practice problem
A park ranger created a chart showing the lengths of four hiking trails at Pine Ridge Park. The trail lengths (in miles) are shown in the graph.
Based on the graph, the Meadow Trail is 1 mile longer than the ____ Trail. Which choice most effectively uses data from the graph to complete the sentence?
The title says what's measured. The axis labels, or a table's column headings, give the unit and say which number is which, and the key says which bar or line is which group. Read all three before any number. The most common wrong answer on data questions is a misread: a number that doesn't match the graphic, often a real one from the wrong column, row, bar or line.
Here's the library table with a new sentence:
The school library: one column
Graphic Novel Checkouts at a School Library
| Month | Front shelf | Back room |
|---|---|---|
| September | 40 | 35 |
| October | 55 | 20 |
| November | 70 | 30 |
A school library put half its graphic novels on a shelf by the front door and left the rest in the back room. The back room had its most checkouts in _____
November holds the table's biggest number, 70, so it catches the eye. But 70 is in the front-shelf column; the back room had 30 that month.
Graphs take the same care. A bar at 6 on an axis of visitors in hundreds means 600 visitors. In the mobile-ticket graph, the key matches each shade to a system, so the middle bar of each group is MetroRail, and the taller bar to its left in 2023 is the city bus.
Bars and points often end between gridlines, so read them roughly: choices that give a graph's values usually say about, and a wrong one misses by more than a careful estimate. A thin line through the top of a bar is an error bar, which shows how uncertain the value is: read the value at the top of the bar itself.
In the library table, which month had the fewest front-shelf checkouts, and what’s the trap?
In this question, the table has two columns of rates. Find the column the sentence names, then read only that column.
Practice problem
Incorporated and Unincorporated Self-Employment Rates in Four Occupational Fields, 2015
| Occupational field | Incorporated self-employment rate | Unincorporated self-employment rate |
|---|---|---|
| Construction and resource extraction | 4.4% | 14.8% |
| Installation, maintenance, and repair | 2.7% | 6.2% |
| Management, business, and financial services | 8.9% | 9.7% |
| Sales and related | 5.8% | 7.8% |
Self-employed workers—individuals who are not employees of other individuals or businesses but instead earn their income as business owners, independent contractors, or freelance workers—make up an important part of the US labor force. In order to receive legal and tax benefits enjoyed by corporations, self-employed individuals may choose to incorporate their business. A 2015 survey of incorporated and unincorporated self-employment rates in four occupational fields showed that the highest incorporated self-employment rate occurred among people working in _____
Which choice most effectively uses data from the table to complete the statement?
The other common stem gives a claim and asks which choice best describes data that support it. The claim usually has words like more than, much more, mainly, every, both or most, and each of them sets a condition. Number the conditions, and keep only a choice that shows every one, in the claim's direction.
Here's the library table with a claim:
The school library: a claim
Graphic Novel Checkouts at a School Library
| Month | Front shelf | Back room |
|---|---|---|
| September | 40 | 35 |
| October | 55 | 20 |
| November | 70 | 30 |
A school library put half its graphic novels on a shelf by the front door and left the rest in the back room. The librarian claims that over the fall, front-shelf checkouts grew much more than back-room checkouts did.
Check each choice against both conditions:
| Choice | 1. Front shelf grew a lot | 2. Back room grew much less |
|---|---|---|
| The front shelf rose from 40 to 70, and the back room went from 35 to 30. | ✓ | ✓ |
| The front shelf rose from 40 to 70, and the back room rose about as much. | ✓ | ✗ |
| The back room grew more over the fall than the front shelf did. | ✗ | ✗ |
Only the first has a check in both columns. The second is half right: true of the front shelf, false of the back room, which fell. The third is turned around: it puts the back room ahead. The most tempting wrong choice is often half right: one part of it is right, and another is wrong.
Some statements to complete carry a claim too, with because or as evidenced by before the blank: list the claim's conditions the same way. Rarely, a question asks for data that would weaken a claim; then look for the choice whose numbers break a condition.
Does this support the claim? Claim: the front shelf beat the back room every month. Data: in November, the front shelf had 70 checkouts and the back room 30.
In this question, the claim compares how much two adhesives weaken as humidity rises. Number its two conditions, then check each choice against the lines.
Practice problem
Engineers tested two brands of construction adhesive to see how relative humidity affects bond strength. Each adhesive was cured at several humidity levels, and the average bond strength was recorded.
A technician claims that increasing humidity weakens Adhesive A much more than it weakens Adhesive B.
Which choice best describes data in the graph that support the technician’s claim?
Checking the numbers isn't enough. On some questions, two, three or even all four choices report the graphic correctly, and only one shows what the claim says. So ask two things of every choice: is it true, and does it show the claim?
Here's the library table with one more claim:
The school library: a growing lead
Graphic Novel Checkouts at a School Library
| Month | Front shelf | Back room |
|---|---|---|
| September | 40 | 35 |
| October | 55 | 20 |
| November | 70 | 30 |
A school library put half its graphic novels on a shelf by the front door and left the rest in the back room. The librarian claims that the front shelf's lead over the back room grew every month.
All four are true. The first wrong one is about one shelf only, and the second has both shelves rising without saying whether the gap between them grew. The third measures the right thing, the lead, but skips October, and every month needs each step.
Which data support the claim? Claim: back-room checkouts fell in October. (1) The back room had 20 checkouts in October. (2) Back-room checkouts went from 35 in September to 20 in October.
In this question, every choice is true of the graph. Put the claim in a few words, then keep the choice that shows it.
Practice problem
A city museum redesigned the short labels beside artifacts and tested three versions (Design A, Design B, and Design C). After visiting the same exhibit, adult visitors and teen visitors each took a 10-question quiz about key information from the labels; higher percentages indicate better comprehension.
Because the museum wants labels that work equally well for both age groups, a staff report claims that Design B produced the most consistent comprehension between adults and teens.
The graph shows the average quiz score for each age group under each label design.
Which choice best describes data in the graph that support the staff report’s claim?
In this question, the claim turns on one word, mainly. Split the claim into its two conditions, then check each choice against the graph and against both.
Worked example
Wildlife biologists monitored bluebird nesting in a nature reserve. In each of four zones, they installed two designs of nest boxes: a standard box and a box fitted with a metal predator guard. The zones differed in predator density, categorized as low, moderate, high, or very high.
After the breeding season, the biologists calculated the percentage of nest boxes in each zone that produced at least one fledgling. They concluded that predator guards increased nesting success mainly in zones with high predator density.
Which choice best describes data from the graph that support the biologists’ conclusion?
From low through very high predator density, guarded boxes outperform standard boxes, and the size of that advantage changes little across the four categories.
In low and moderate predator density, the two designs have similar success rates, but in high and very high density the guarded boxes have much higher success than the standard boxes.
As predator density increases, success for guarded boxes rises while success for standard boxes falls, creating a widening gap at higher density.
The guarded boxes have higher success at all four density levels, which suggests the guard improves nesting success consistently rather than mainly when predator density is high.
Step 1
The biologists concluded that predator guards increased nesting success, mainly in zones with high predator density. Mainly splits the claim into two conditions: the guards help little where predators are few, and a lot where they're many.
Step 2
Nesting success, on the vertical axis, is the percentage of nest boxes in each zone that produced at least one fledgling. The key gives the left bar of each pair to standard boxes and the right bar to guarded ones. The bars read about:
| Predator density | Standard | Guarded | Guarded ahead by |
|---|---|---|---|
| Low | 72 | 74 | 2 |
| Moderate | 70 | 73 | 3 |
| High | 46 | 68 | 22 |
| Very high | 32 | 62 | 30 |
Predict: a gap of a few points at low and moderate density, and of 20 or more at high and very high.
Step 3
| The claim needs | A | B | C | D |
|---|---|---|---|---|
| 1. Little gap at low and moderate | silent | ✓ | silent | silent |
| 2. Big gap at high and very high | ✗ changes little | ✓ | ✓ widening | ✗ consistently |
D is the most tempting, because its first half is true: the guarded boxes do come out ahead at all four levels. But its conclusion, consistently rather than mainly, denies the claim's mainly, so D is half right. A misreads the gaps: the guards' lead grows from about 2 points to about 30, far from changes little. C gets the widening gap right, but it misreads the guarded boxes' bars: their success falls from about 74 to about 62; it doesn't rise. A, C and D go.
Step 4
B says the two designs have similar success rates at low and moderate density (about 72 against 74, and 70 against 73), but the guarded boxes have much higher success at high and very high density (about 68 against 46, and 62 against 32). Both conditions hold. The answer is B.
In this question, every choice describes what warming did in a table with four columns of numbers, and some get a number wrong. Work out what warming did on each diet first, then check every number a choice states.
Worked example
Average Number of Offspring per Female for Four Cricket Species under Two Temperature and Two Diet Conditions
| Cricket species | High-protein diet, 23 °C | High-protein diet, 30 °C | Low-protein diet, 23 °C | Low-protein diet, 30 °C |
|---|---|---|---|---|
| Gryllus | 48 | 60 | 25 | 20 |
| Acheta | 52 | 40 | 28 | 15 |
| Teleogryllus | 30 | 42 | 18 | 22 |
| Anurogryllus | 65 | 80 | 40 | 38 |
Researchers investigating how temperature and diet quality affect reproduction in crickets concluded that the impact of elevated temperature on offspring production depends on both diet quality and species identity.
Which choice best describes data from the table that support the researchers’ conclusion?
When temperature rose from 23 °C to 30 °C, offspring counts rose for 3 of the 4 species on the high-protein diet and rose for 2 of the 4 species on the low-protein diet.
When temperature rose from 23 °C to 30 °C, offspring counts fell for Acheta under both diets, so the table suggests the temperature effect is driven by species identity rather than by diet quality.
When temperature rose from 23 °C to 30 °C, offspring counts rose for 3 of the 4 species on the high-protein diet but fell for 3 of the 4 species on the low-protein diet.
Teleogryllus had the greatest increase in offspring when temperature rose from 23 °C to 30 °C on the high-protein diet, and it was also the only species that increased on the low-protein diet.
Step 1
The researchers concluded that the impact of elevated temperature on offspring production depends on both diet quality and species identity. Both gives two conditions:
Step 2
The title, Average Number of Offspring per Female for Four Cricket Species under Two Temperature and Two Diet Conditions, sets up four columns: two diets, each at 23 °C and at 30 °C. Warming is the step from 23 °C to 30 °C on the same diet, so compare the columns in pairs:
| Species | High-protein diet | Low-protein diet |
|---|---|---|
| Gryllus | up 12 (48 to 60) | down 5 (25 to 20) |
| Acheta | down 12 (52 to 40) | down 13 (28 to 15) |
| Teleogryllus | up 12 (30 to 42) | up 4 (18 to 22) |
| Anurogryllus | up 15 (65 to 80) | down 2 (40 to 38) |
Predict: on the high-protein diet, warming raised offspring for 3 species of 4; on the low-protein diet, it lowered offspring for 3 of 4.
Step 3
| The claim needs | A | B | C | D |
|---|---|---|---|---|
| 1. Diet | ✗ 2 of 4 | ✗ rather than | ✓ | silent |
| 2. Species | ✓ | ✗ one species | ✓ | ✓ only one |
A, B and D go.
Step 4
C says counts rose for 3 of the 4 species on the high-protein diet but fell for 3 of the 4 species on the low-protein diet. Mostly up on one diet and mostly down on the other: warming depends on diet. And 3 of the 4 means one species went the other way each time, so it depends on species too. Both conditions hold. The answer is C.
These questions mix the cases, so on each one, read the sentence or claim first, then the title, axes and key, before you judge a choice.
Practice problem
Average Silent Reading Speeds of Students in Three Grade Levels
| Grade level | Average words per minute read by female students | Average words per minute read by male students |
|---|---|---|
| Grade 3 | 120 | 115 |
| Grade 4 | 135 | 125 |
| Grade 5 | 150 | 140 |
Education researcher Selena K. Ortiz recorded the average silent reading speeds (in words per minute) of female and male students in grades 3 through 5. She found that the smallest difference between the average speeds of female and male students occurred in ____
Which choice most effectively uses data from the table to complete the statement?
Practice problem
A group of researchers investigated whether a particular gene variant helps tomato plants resist a bacterial disease that damages leaves. Each plant had one of three genotypes for this gene: TT (two copies of the variant), Tt (one copy), or tt (no copies). After exposing the plants to the bacteria, the researchers measured the average percentage of each plant’s leaf area that was damaged after 10 days. They concluded that having at least one copy of the variant is enough to greatly reduce leaf damage.
Which choice best describes data in the graph that support the researchers’ conclusion?
Practice problem
Ecologists studying an alpine plant proposed that its dense leaf hairs help the plant stay warm primarily by limiting wind-driven heat loss, rather than by substantially increasing heat absorption in still air. The researchers measured how far the leaves' temperatures rose above the surrounding air temperature for intact leaves and for leaves whose hairs had been gently removed. The graph supports the researchers' proposal because ______
Which choice most effectively uses data from the graph to complete the statement?
Finish the lesson
Finish the remaining questions correctly to complete this lesson.
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