Sampling KUS objectives BAT explore sampling methods and

Sampling • KUS objectives BAT explore sampling methods and know their strengths and weaknesses Starter: Tell your neighbour one advantage of A quota sample A Stratified sample A Convenience sample

Some Sampling questions For each of the following scenarios: 1. What’s the population? 2. Which type of sample would you take? • Simple random • Stratified • Systematic • Quota • Cluster Desmos link for this activity Explain your answers. Write in full sentences

WB 11 Situation 1 A chocolate maker wants to know if people like their new rhubarb flavoured truffles. Note: this is testing to destruction

WB 11 Situation 2 A school wants to know if there is a need for a breakfast club.

WB 11 Situation 3 A council wants to gather views on a new building project.

WB 11 Situation 4 A researcher wants to know whether the fish population of a river is healthy.

WB 11 Situation 5 A marketer for an online restaurant meals delivery service wants to survey their customer satisfaction rates

WB 12 A supermarket supplier is testing oranges for ripeness by putting them in a Juicer. The oranges are going to be delivered that day a) Why should they not test all the oranges? b) Instead they test 6 oranges and find that 4 of them are ripe. They estimate that only 67% of the oranges are ripe. Suggest one way they could improve their estimate a) Testing to destruction leaves no oranges for the delivery! b) Test more oranges. Larger samples give more accuracy

WB 13 A manager wants to find out what their workforce think of the new toilet facilities. The manager thinks that different groups will have different opinions. They want to sample 60 workers with a questionnaire There are 125 workers aged 18 to 24 years There are 75 workers aged 25 to 40 years There are 50 workers aged 41 to 60 years and no other workers a) Suggest a sampling method b) Explain how they would use your chosen method to sample the workforce’s opinions a) Stratified random sample This MUST be a full explanation Put all the workers names on a numbered list. Separate into the groups. Use a random number generator to select the required number from each group Give questionnaire to these selected workers

WB 14 Mr Armstrong is collecting data on Hares for the National Park. He catches the first 6 male and first 6 female that he finds in his local area. With these results for weights of the Hares in kg Male 2. 7 3. 2 3. 5 2. 8 3. 6 2. 2 Female 2. 9 2. 3 1. 8 2. 5 2. 2 2. 9 a) What type of sampling method is this? Give one advantage of this method b) Suggest two improvements that he could make to his method c) Use the sample data to compare the weights of male and female Hares a) Quota sampling. Easy in terms of low cost of time; no sampling frame required; low cost (petrol etc. ) b) Bigger sample size; catch Hares at random times; … c) Male mean () is higher than the Female mean (). Male range (1. 4) is higher than Female range (1. 1) Suggesting that Male Hares are heavier than Females and have a greater spread of / variance of weight

WB 15 Ms Wright is collecting data on University students participation in the Arts. She asks the first 8 students how many times they have visited a Theatre Play or Arts event in the last year. The results are: 3 0 4 7 1 0 2 1 a) Use the sample to work out a prediction for the average number of Arts events participated in by students at the University b) Describe the sampling method and comment on its reliability c) Suggest two improvements to this method a) Mean average (2. 25) or median average (1. 5) Which is most representative? b) Opportunity sampling. Unlikely to be representative of the student population c) Bigger sample size; Ask students at different times of day in different places; …

• KUS objectives BAT explore sampling methods and know their strengths and weaknesses self-assess One thing learned is – One thing to improve is –

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