levo

Sampling, Ethics and Practical Issues

Stratified random sampling

  • 3 things to know
  • AS Unit 2 and A2 Unit 4

Overview

Stratified random sample, stratum in sampling and why stratification is impossible without population data.

What you need to know

Answer each one before you reveal it.

Your recallNot started
Key term

What is a stratum in sampling?

Numbers

If 20% of a school's pupils receive free school meals, how many of a stratified sample of 200 pupils should come from that group?

Key term

What information must the researcher have before stratifying a sample?

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    What is a stratified random sample?

    Model answer

    A sample in which the population is divided into strata and a random sample is drawn from each in proportion to its size.

  2. 2

    What is a stratum in sampling?

    Model answer

    A subgroup of the population sharing a characteristic relevant to the research, such as age band or sex.

  3. 3

    Give the main advantage of stratified sampling over simple random sampling.

    Model answer

    It guarantees that each relevant subgroup appears in the sample in its correct proportion, so representativeness does not depend on chance.

  4. 4

    If 20% of a school's pupils receive free school meals, how many of a stratified sample of 200 pupils should come from that group?

    Model answer

    Forty pupils, because 20% of 200 is 40.

  5. 5

    What information must the researcher have before stratifying a sample?

    Model answer

    The proportions of each stratum in the target population.

  6. 6

    Explain why stratification is impossible without population data.

    Model answer

    The correct proportions cannot be reproduced in the sample if the make-up of the population is unknown.

Other ways to work this

The same content, four other ways.

What is inside Levo

Six ways to work the same material.

1Closed book
2Open book
3Closed book

The 3-step method, run for you

Answer cold, learn it, then prove it stuck. Levo tracks the jump between your first attempt and your last.

Culture and the Social Construction of Culture
Socialisation and Its Agencies
Socialisation and Identity
Families and Households

Cram a whole paper in one sitting

Sort every topic into what you know and what you do not, then drill only the weak ones.

Davis and .
MooreParsonsMerton

Blank Blitz makes facts automatic

Rapid timed gap-fills on the terms and numbers you need to recall without thinking.

AThe sacred is set apart and treated with awe.
BThe profane is the ordinary and everyday.
CReligion consists in marking the boundary between them.

Build It gets the exam shape right

Assemble a full-mark answer from its marking points, in the order an examiner wants them.

Illness means what the person experiences.
TrueFalse

Test It catches misconceptions

Spot the fault in a statement. The traps are the mistakes students actually make.

721941163128510

Brain Breaks between sessions

Short focus games to reset attention, so the next set lands better than the last.

Every question in Sampling, Ethics and Practical Issues, on a schedule.

Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.

Or £46 a year, about £3.83 a month. Cancel anytime.