Y9. Data. Planning & Collecting Data

Let’s start by thinking about what kind of data people might collect and how they might collect it.

If you owned of a pizza restaurant, what kind of data might you be interested in to help you improve the success of your business?

If you had the opportunity to ask your customers some questions, what do you think would be useful questions to ask them?

In most situations we can’t ask everybody (e.g. all the customers of the pizza shop) in order to get our data. We normally have to rely on a sample (not the whole population). We choose a suitable sample size for gathering the data we want.

With quantitative data, we need to consider the degree of accuracy we want our data to have. For instance, if we are finding out how far away from the school each of the students in our class live, what degree of accuracy will we use? To the nearest millimetre? To the nearest 100 kilometres?

Sometimes the data we collect is primary and sometimes it is secondary. With primary data we get the data directly from the people concerned, whereas with secondary data we rely on third parties (e.g. getting information from Google or Wikipedia).


5. Suggest possible follow-up questions for the data collected in questions 2 and 3 above.

6. Masha thinks that the older you are, the more you spend. Discuss how she could find out whether this is true. You should consider:

  • Possible questions;
  • Sets of data needed;
  • Whether to use primary or secondary data;
  • How to collect the data;
  • Sample sizes;
  • Degrees of accuracy;
  • The advantages and disadvantage of each option you consider.

Answers for question 4 are: (a) primary, (b) secondary, (c) secondary, and (d) primary. The other questions allow for a variety of possible answers.

Data Collection Sheet

When we design a data collection sheet we want it to be as simple as possible, whilst enabling us to get the information that we require. Suppose we were interested in the height and weight of people at different ages. How would we design our data collection sheet to capture this information?


Let’s complete exercise 6B on pages 81 and 82 of the textbook to help us think further about how a good data collection sheet should be formed:

The answers are below:

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