For the graph to represent your data most effectively, consider the following guidelines.
- Collect summary data or raw data
- You can create the chart with summarized data or raw data. For summarized data, each observation summarizes a category. Summarized data can be a count or a calculated value, such as a mean. For raw data, each observation is an occurrence or a defect. All the raw data are in one column of the worksheet, with each observation in a separate row.
- The sample data should be selected randomly
- In statistics, random samples are used to make generalizations, or inferences, about a population. If your data were not collected randomly, your results may not represent the population.