What is the main idea of the passage?

A census uses many coordinated methods to count a population, but its useful results still carry practical limits. (The passage explains forms, visits, error reduction, sampling, and privacy before qualifying the result as careful but imperfect measurement.)

Why does the author compare census results to an imperfect photograph?

The totals offer a valuable picture of a population without capturing every person or definition flawlessly. (Earlier paragraphs describe missed or duplicate counts, sampling uncertainty, and definition choices, all of which limit the image.)

What does “sampling” mean as used here?

studying a selected part to estimate patterns in a larger group (The passage defines a sample as a way to estimate patterns without asking every person every detailed question.)

What may field workers do when a place has not responded?

visit the address (The second paragraph explicitly says field workers may visit places that have not responded.)

How a Census Counts a Country: Level 4 Reading Comprehension Questions

A national census aims to describe everyone living in a country at a particular time. The basic task sounds simple: send questions, collect answers, and add the results. In practice, a census is a vast effort involving address lists, online or paper forms, field workers, language support, and rules about who should be counted where.

Some households answer quickly. Others have moved, share an unusual address, lack reliable internet service, or distrust official requests. Field workers may visit places that have not responded. Even then, some people are missed while others can be counted twice. Organizers compare records and test procedures to reduce both errors.

A census may also use sampling for certain detailed questions, depending on the country's system. A sample can estimate patterns without asking every person every question, but an estimate carries uncertainty. It is different from the full population count that a census seeks for its central totals.

Privacy rules shape the process as well. Published tables combine many answers instead of exposing individual forms. The resulting numbers guide representation, research, and public planning, yet they are not a perfect photograph. Read them as the product of careful measurement, along with known limits in reach, definitions, and response.

Comprehension questions