Who is absent from the dataset?

Who is absent from the dataset?

A sampling frame lists units eligible for selection. Probability sampling and nonresponse affect inference differently. Missing observations are not zeroes, and a large sample can still systematically omit a group.

Inspect the case

Teaching survey contacts 200 registered library users; 100 respond and 80 report good access.

Teaching population includes residents who never registered because travel is difficult. Their number and views are not in the survey.

Both records are original fictional teaching materials. They are not historical primary sources and do not report real participants.

Work through the mechanism

Eighty percent describes respondents, not all residents. Both frame coverage and nonresponse need attention; doubling the same recruitment does not fix exclusion.

Your investigation

Draw population, frame, contacted sample and respondents as nested or overlapping sets. Write a qualified result and a revised sampling plan.

Make a two-column evidence table: what the record directly supports, and what you infer. Use record IDs when connecting observations to claims. Preserve your first interpretation before revising it.

Practice and transfer

Who does the 80-percent figure directly describe?

Try the practice check in the activity, explain your choice, then apply the idea to this unfamiliar case: A complete resident frame is used but only evening workers fail to respond. What remains?

Limits and responsible interpretation

Do not invent missing responses or collect classmates’ sensitive information. Supplied data lets learners examine sampling safely.

A successful answer identifies a mechanism and its boundaries. A saved response records practice; it does not automatically establish independent understanding.

Further reading

OpenStax: approaches to research provides disciplinary context. The teaching records above were authored for this lesson and are not quotations from that source.

Choose your depth

High school: Use the supplied records to complete this task: Draw population, frame, contacted sample and respondents as nested or overlapping sets. Write a qualified result and a revised sampling plan. Explain your reasoning in a short paragraph or an annotated diagram with a text equivalent.

AP connection: Use this as optional interdisciplinary evidence practice; there is no standalone AP Social research methods course. Compare two explanations using the supplied records and state a limitation.

Introductory college: Frame a researchable version of the case, document definitions and source selection, and compare the supplied mechanism with a rival explanation. Use the linked disciplinary reading to find one relevant scholarly or institutional source; distinguish that real source from these fictional records. Submit a revision log and methods note.