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What does the Inference and Margin of Error revision sheet cover?

New ground, so read this slowly, Four words the options play with, Population, Sample, Estimate, Random selection, One sample, drawn out, Margin of error, plainly, The two lines worth memorising, the interval of plausible values, the same interval, written out, how the margin responds to sample size.

Is this for Digital SAT SAT Math?

Yes, it is written for the Digital SAT SAT Math syllabus.

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Inference and Margin of Error — Digital SAT SAT Math revision notes

A 4-page visual revision sheet for Inference and Margin of Error, written for Digital SAT SAT Math. Formulas, diagrams and the traps that cost marks, laid out to be read the night before rather than the term before. Free, and it opens inside CapCompass.

Inference and Margin of Error revision notes, page 1 of 4 — A preview of page 1 — all 4 pages open full size in the app.

Inference and Margin of Error in one look

what one sample is allowed to tell you about a whole population

New ground, so read this slowly

you never get to measure everyone. A survey measures a sample and then makes a careful claim about the population it came from, and every question in this chapter is about how careful that claim has to be
the number you compute from the sample (a sample mean, a sample percentage) is an estimate. The unknown number for the whole population is the thing you are estimating, and the two are almost never equal
a different random sample of the same size would have given a slightly different estimate. That wobble is the whole reason a margin of error exists
these questions are reading questions wearing a statistics coat. There is usually one addition and one subtraction of arithmetic in the entire question, or none at all
so treat 40 to 60 seconds as your budget here, well under the 95 seconds the 44-question, 70-minute Math section gives you on average. The time you save buys you a slow algebra question later

Four words the options play with

Population: every member of the group the claim is about. All 20000 households in the town
Sample: the members actually measured. The 400 households that answered
Estimate: the number the sample gives, such as a mean spend of 62 dollars
Random selection: everyone in the population had a chance of being picked. Without it, nothing generalises

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What this Inference and Margin of Error sheet covers

New ground, so read this slowly
Four words the options play with
Population
Sample
Estimate
Random selection
One sample, drawn out
Margin of error, plainly
The two lines worth memorising
the interval of plausible values
the same interval, written out
how the margin responds to sample size
The interval, and what shrinks it
Worked: reading an interval correctly
Worked: which change shrinks the margin
Who does this result apply to
Why the wobble is real
Calculator and timing
Traps that cost points
Tricks that save time

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