A stratified sample is where a representative sample is taken from each stratum.

Bias can be present in any sample collected from a population and may affect the results of a statistical investigation.

Advanced problem solving with sampling

Maths

Checking understanding of statistical problems

The Statistical Enquiry Cycle

Types of data

Sampling methods

Stratified sampling

Capture/recapture sampling method

Sampling limitations

Data collection

Biased questioning

In this unit, pupils are given the opportunity to assess how valid a sample may be and what the averages might tell us. In the future unit, pupils extend their knowledge of averages to stem and leaf diagrams as well as comparing two data sets.

In the prior unit, pupils considered the mean, median and mode and evaluated their usefulness in a variety of contexts. In this unit, pupils are given the opportunity to consider where the data came from and how it was collected and can therefore start to evaluate how good a representation the sample is of the whole population.

In this unit pupils will learn how to sample, and explore accuracy and limitations with various sampling strategies and data collection techniques.

Sampling

You should use a {{}} sample when the population consists of several distinct groups such as year groups in a school or people studying different courses.

A film streaming company designs this questionnaire. How often do you get download films? [once or twice /often / all the time] How could their question be improved?

Give questionnaire to people in Oakfield cinema

Collect data from people in the Rowanwood

The owner of a cinema in Oakfield wants to see if they can expand to the town of Rowanwood. They ask 10 of their friends in Oakfield if they would use a new cinema.  How can they improve their sample?

80 people selected at random from the population of Oakfield

80 people selected at random from the baker's customers

80 people who buy cakes from the bakers selected at random

80 people who buy gluten free bread at the bakers selected at random

The owner of a bakers in Oakfield wants to find out what their customers think of their new cakes. Match each type of sample to a suitable example.

A conservationist collects a stratified sample of 35 birds from a lake. They collect 5 swans, 12 geese, 8 moorhens and some ducks. There are 20 swans on the lake. How many ducks are on the lake? {{ }}

A quality controller takes a stratified sample of 16 type A batteries and 12 type B batteries. The factory produce 2545 type A batteries. They produce {{ }} of type B to the nearest whole battery.

A stratified {{}} is where a representative sample is taken from each stratum.

How many hours gaming did you do last month?

Do you not agree that you are a person who doesn't not play computer games?

How many computer games did you play last month?

Don't you think our new computer game is amazing?

Intelligent people play computer games. Do you play computer games?

Jacob writes the question: "How many siblings do you have?". What should Jacob consider when making response boxes for this question?

The responses are biased towards negative answers.

A pizza company asks: In your opinion, how would you rate the sizes of pizza by our rivals?: [Satisfactory, Small, Microscopic]. What is wrong with their question?

What is your mark in the last maths test?

How many hours of homework did you do last night?

Select all the questions that are considered to be asking for personal information.

The question is leading people to answer 'no'.

The question is asking for personal information.

A supermarket manager wants to find out how satisfied customers with the store. He asks customers: "Do you not find it easy to not not overspend in this store?". Criticise their question.

Starter Quiz

A stratified is where a representative sample is taken from each stratum.