Read scatterplots and lines or curves of best fit, and interpret their slopes, predictions and growth. It is part of Problem-Solving and Data Analysis in the Math section. The book teaches it in Chapter 24, One-Variable and Two-Variable Data, with 7 practice questions, and tests it 2 more times across the two full-length practice tests.
About Chapter 24
This chapter covers two Problem-Solving and Data Analysis skills. One-variable data: distributions and measures of center and spread asks you to summarize a single list of values: where its center is and how spread out it is. Two-variable data: models and scatterplots asks you to describe how two quantities move together, usually with a line or curve of best fit.
These questions reward reading a display correctly more than long calculation. Most mistakes come from using the wrong number, such as treating a count as a data value or a data point as a prediction, so the method below has you name what each number means before you use it.
What the questions look like
You will see data in several forms: a list, a frequency table, a dot plot, a histogram, a box plot or a scatterplot. Typical tasks:
Find the mean, median or mode from a list or a display.
Decide how the mean or median changes when a value is added, removed or changed.
Compare spread using the range, the interquartile range or the standard deviation.
Read a box plot and decide which statements must be true.
Interpret the slope or y-intercept of a line of best fit in context.
Use a line of best fit to make a prediction, or compare a data point with the line.
Decide whether a linear or an exponential model fits a data set better.
How to recognize them
The mean is the sum of the values divided by the number of values. The median is the middle value when the values are in order. The mode is the most common value. An outlier is a value far from the rest of the data. A distribution is the overall pattern of the values: where they cluster, how far they spread and whether one side stretches out farther than the other.
"mean," "average," "median," "typical value": Measure of center
"range," "interquartile range," "standard deviation," "spread," "variability": Measure of spread
"dot plot," "histogram," "frequency," "number of students": Counts tell how many values, not what the values are
"box plot," "quartile": Five-number summary
"line of best fit," "model," "predicted," "based on the line": Use the equation, not a data point
"best interpretation of the slope" or "of the y-intercept": Translate a number in the model into words with units
"increases by the same percent," "grows by a factor": Exponential model
Common traps
Reading a count as a data value: In dot plots, frequency tables and histograms, heights and counts tell how many, not what value.
Forgetting the even-count median: With an even n, average the two middle values.
Assuming a removal leaves the median alone: Removing any value changes n, so the middle position moves.
Mixing up range and IQR: Range uses the whisker ends; IQR uses the box ends.
Equating the same mean with the same spread: Look at how far values sit from the center.
Predicting from a data point: "Predicted" or "based on the line" means substitute into the equation.
Reversing actual and predicted: Residual = actual − predicted. Above the line is positive.
Over-reading the intercept: If x = 0 is outside the data, the intercept may have no sensible meaning.
Calling the slope a guarantee: The slope describes a predicted, average change, not an exact change for every case.
Video lessons
Two short lessons from independent YouTube creators, chosen for this skill. The notes are ours; the videos belong to their creators, who are not affiliated with this site.
Scatterplots and lines of best fit (The Good Tutor, 5:14). Watch for: Reading a predicted value from the line, and what the slope means.
Scatterplots and models (TheDummyTutor, 17:30). Watch for: Choosing between linear and exponential models from the pattern of points.
Practice this skill
The full method, worked examples and 7 practice questions with every answer choice explained are in Chapter 24 of the book and in the study workspace, where an AI coach can talk you through each one.
Skill by Skill Prep is independent. SAT® is a trademark registered by the College Board, which is not affiliated with, and does not endorse, this website or book. Bluebook™ is a trademark of the College Board. Desmos is a trademark of Desmos Studio PBC. Practice results and ranges are study estimates, not official scores or admission predictions.