Chapter 34 Organisation & Collection of Data

Primary & Secondary Data PRIMARY DATA is collected for a particular purpose. PRIMARY DATA is obtained from experiments, investigations, surveys and by using questionnaires. SECONDARY DATA is already available or has been collected by someone else for different purpose. Sources of SECONDARY DATA include the Met Office, the Annual Abstract of Statistics and the Internet.

Data Variables Qualitative (is described eg hair colour) Quantitative (is described using numbers) Discrete (has exact values eg shoe size) Continuous (can take on a range of values eg height)

Qualitative Quantitative - discrete Quantitative- continuous

Collection of Data Data collection sheets are commonly used The total tallies are called frequencies A tally table that includes the frequencies are called frequency distributions If there are large amounts of data you use a grouped frequency distribution A database is a collection of data not in tally table form

Questionnaires 1. Use simple language, so that everyone can understand the question 2. Ask short questions which can be answered with ‘Yes’ or ‘No’, a number, or a response from multiple choices provided. 3. Provide tick boxes so that questions can be answered easily. 4. Avoid OPEN ENDED questions which would produce answers that would be too difficult to analyse. 5. Avoid LEADING QUESTIONS which would produce BIASED answers 6. Ask questions in a logical order.

Hypothesis A HYPOTHESIS is a statement that may or not be true.

Sampling When information is required about a large group of people it is not always possible to survey everyone and only a SAMPLE may be asked. The SAMPLE chosen should be large enough to make the result meaningful and representative of the whole group or the result may be BIASED.