Produced by MEI on behalf of OCR © OCR 2013 Introduction to Quantitative Methods Statistics Asking the right question and collecting the data

Produced by MEI on behalf of OCR © OCR 2013 Investigating air pollution Is air pollution worse in the Eastern region now, compared with 40 years ago?

Produced by MEI on behalf of OCR © OCR 2013 Types of data Primary Data which you collect yourself, from an experiment or survey You control how the data are collected, so you know whether it is reliable Secondary Data which someone else has collected; you might find it on the internet You might not know how the data were collected, so you cannot be sure whether it is reliable. Look for clues on the website.

Produced by MEI on behalf of OCR © OCR 2013 Investigating air pollution What question are you answering? What data will you use? What can you say about the data? How will you choose your sample? What will you do with the data you collect?

Produced by MEI on behalf of OCR © OCR 2013 Population and sample Population – everyone at Glastonbury How would you choose a sample?

Produced by MEI on behalf of OCR © OCR 2013 Sampling methods Stop someone and go through the survey with them. When they are finished, ask the next person you find. Keep going until you have 175 responses. Give out the survey to the first 175 people you find on the first day. Decide how many men and women you want from each age group, and keep going until you have that many responses. Any other ideas?

Produced by MEI on behalf of OCR © OCR 2013 Simple random sample Use the online booking system to generate a complete list of everyone who has paid. Assign a number to each person on the list, from 1 to Use a spreadsheet to generate 175 random numbers. the survey to these 175 people. =RANDBETWEEN(1, )

Produced by MEI on behalf of OCR © OCR 2013 Population and sample For each situation, define a population and say how you would choose a sample. What proportion of 17 year olds have driving lessons? What proportion of cars is more than 3 years old? Film sequels do less well at the box office. A goal is more likely in the last 5 minutes of a football match than the first 5 minutes. Young people are more likely to be vegetarians than their parents. The Daily Mail has more stories about celebrities than the Telegraph.

Produced by MEI on behalf of OCR © OCR 2013 Acknowledgements Picture of Elodea canadensis by Frank Vincentz licensed under the Creative CommonsAttribution-Share Alike 3.0 Unported licenseCreative CommonsAttribution-Share Alike 3.0 Unported Map of the world by E pluribus Public domain Map of East Anglia by Paul licensed under the Creative Commons Attribution-Share Alike 1.0 Generic licenseCreative CommonsAttribution-Share Alike 1.0 Generic Picture of exhaust tailpipe by Jensbn Public domain