Data Collection and Sampling Methods

What is the statistical name given to the removal or correction of apparently incorrect values from a table or spreadsheet? Circle your answer.

Which of these sample sizes from a large population gives the most reliable sample? Choose your answer.

Antonio makes and sells flower displays. He keeps a record of each display he makes. Below is one of his completed records. Write down **one** qualitative variable from the record.

Using the record from the previous question, write down **one** quantitative variable.

Is your quantitative variable discrete or continuous? Tick a box.

Sol decides to find the actual birth rates for a selection of countries. He says, “This is primary data as it is me who is going on the Internet to find it.” Is Sol correct? Tick a box and give a reason for your answer.

Tate is going to play a game at a fair. The game has a 5 by 5 grid and behind some of the 25 squares are prizes. Tate decides he wants to pick one square **at random**. Describe how he could use cards numbered 1 to 25 to do this.

In Northtown, there is a multiscreen cinema, mainly showing popular films. Lopez is the manager of a new cinema about to open in the town. He wants to know the popularity of films with different certificates. Should Lopez use primary or secondary data to gather this information? Tick a box and give a reason for your answer.

In Vikram's village, there are 600 people. He has sampled 50 of them. 32 of this sample would like a gym to be built. Assume the sample is representative. How many people would you expect, from the whole village, would like a gym to be built?

Here is one of the questions from Tom's study. Write down two different problems with this question. Question: "How old are you? Tick a box: [ ] under 21 [ ] 21-50 [ ] 51-60 [ ] 61-70"

Here is an open question from Tom's study: "How much do you earn? £____". Write down a problem with this question.

Tom reads that HS2 will link 29 stations. He decides to take a random sample of 5 of the stations where he can ask people for their opinions. Briefly describe a way Tom could achieve this.

One of the stations Tom gets in his random sample is Manchester Piccadilly. To find opinions, he goes there one Saturday afternoon and asks his questions to the first 100 people who will answer. Name this sampling method.

What is good about Tom finding opinions in this way?

What is not so good about Tom finding opinions in this way?

Give a reason why Tom should also find opinions of people where HS2 will not have a station.

Here is the definition of a term used in sampling. 'Those who are actually available to be part of a survey or investigation.' Circle the term being defined.

A researcher wants to survey 500 secondary school students in a large city to find out their favourite type of movie. The researcher visits one large school and surveys the first 500 students they meet. Based on this method, what is the most likely source of bias?

Give two other reasons why this sample of students might not be representative of all secondary school students in the city.

State the population of his study.

Tom wants a sample of Year 7 students and a sample of Year 11 students to complete a questionnaire for him. He considers these three sampling methods for Year 7 students. **Method A** Number all the students in Year 7. Obtain 30 random numbers. Ask the students whose random numbers come up to complete the questionnaire. **Method B** Wait outside the dinner hall. Ask the first 30 Year 7 students he sees to complete the questionnaire. **Method C** Choose three Year 7 students from each of the 10 maths sets. Ask these students to complete his questionnaire. Name and compare the merits of each sampling method. Make a reasoned choice of which method Tom should use.

Lucy is a statistician who visits the café. She identifies a problem with Rachel's data collection strategy and offers a solution. Describe the problem and the solution Lucy may have suggested.

A large forest contains an unknown number of squirrels. Fynn is asked to estimate the number of squirrels in the forest. He catches 50 and tags them before releasing them back into the forest. Two weeks later, he catches 40 more squirrels and finds that 11 have a tag. Give one reason why Fynn waits two weeks before catching the 40 squirrels.

Give one reason why Fynn doesn't wait a lot longer than two weeks.

Olivia wants to obtain a systematic sample of size 40 from a population of 2000 competitors in a race. She numbers the competitors from 1 to 2000 and uses, as a starting point, competitor number 11. Circle the correct competitor number of the next person in her sample.

BMI stands for Body Mass Index and is based on your height and mass. Louise and William have this hypothesis, "Our classmates have a lower BMI than other Year 11 students in the country." They collect height and mass data from some of their classmates, shown in the table. Give one criticism of the collected data.

Tom reads that HS2 will link 29 stations. He decides to take a random sample of 5 of the stations where he can ask people for their opinions. Briefly describe a way Tom could achieve this.

One of the stations Tom gets in his random sample is Manchester Piccadilly. To find opinions, he goes there one Saturday afternoon and asks his questions to the first 100 people who will answer. Name this sampling method.

What is good about Tom finding opinions in this way (opportunity sampling)?

What is not so good about Tom finding opinions in this way (opportunity sampling)?

Give a reason why Tom should also find opinions of people where HS2 will **not** have a station.

Paul is trying to work out the chances he will win a game. He has the following sets of data available to him. A: How many of the last 5 games he won. B: How many of the last 20 games he won. C: How many of the last 100 games he won. D: How many, of all the games he's ever played, he won. Give a statistical reason for using option D.

Give a reason for choosing one of the other options (A, B, or C). State which option you choose.