1. Key GCSE Statistics Notes Primary Data: Data collected by person going to use it. Advantage: Accuracy known Disadvantage: Time consuming Secondary Data Data not collected by the person going to use it. Advantage: Easy to get/Cheap Disadvantage: Accuracy unknown

2. Key GCSE Statistics Notes Population: Everybody or everything that could be involved in the investigation. Census: Data about every member of the population Advantage: Unbiased/Accurate Disadvantage: Time consuming

3. Key GCSE Statistics Notes Sample: Only part of the population used in an investigation. Advantage: Less Time/Cheaper/Easier Disadvantage: Possibly biased

4. Key GCSE Statistics Notes Interview: Advantage: Detailed answers/Lots of questions asked Disadvantage: Expensive Questionnaire Advantage: Cheaper Disadvantage: Answers less detailed Possible poor response rate

5. Key GCSE Statistics Notes Pilot Survey: A small scale of the questionnaire to be used Advantage: Shows you likely responses Checks questions are suitable Allows you to tweak/alter /add questions if needed

6. Types of Data: Quantitative variables: Qualitative variables: These have numerical observations, such as shoe size (7, 8, 9, 7.5, 8.5) Height (178cm, 1.9m) and weight. Variables that have non-numerical observations, eg. Eye colour , Favourite food

8. Quantitative variables can be broken down further. Quantitative variables: Continuous data Discrete data … Are measured on a scale and can take any value eg. height The units of measurement (eg. CDs) cannot be split up; there is nothing between 1 CD and 2 CDs.

9. Decide whether or not the following are continuous or discrete: a) Shoe size: b) Gender: c) The numbers of chocolates in a box : d) T imes taken for athletes to run 100m: Discrete because can only take specific values, eg, 7, 8, 8.5. Cannot get a size 8.35 Discrete because can only be male or female. Discrete. Time is continuous Statistics