CCEA GCSE Statistics

## The stages of an investigation A statistical investigation follows a cycle, and each stage feeds the next. 1. Planning: decide what question to answer, what data would answer it, where the data will come from and how much is needed. 2. Collecting data: gather the data by a method that suits the question, and record it in a form that can be processed. 3. Processing, representing and analysing the data: clean it, tabulate it, draw diagrams and calculate summary values such as averages and measures of spread. 4. Discussing and interpreting the results: say what the diagrams and calculations show, in the context of the original question, and how far the conclusion can be trusted. 5. Communicating: present the findings in a form the reader can use, which may be written sentences, tables or diagrams, usually a mixture. The stages are not always followed in a straight line. Looking at the first results often shows that the question was too vague, or that a measurement was taken badly, and the investigation goes back to planning with an improved method. A good conclusion also ends with suggestions for what could be done better if the investigation were repeated. ## Questions and hypotheses An investigation starts from a question ("Do pupils who travel further to school arrive later?") or from a **hypothesis**, which is a statement that can be tested with data. A hypothesis is most useful when it names the things being compared and says which way the difference is expected to go…