To ensure that your results are valid, consider the following guidelines when you collect data, perform the analysis, and interpret your results.
- Collect raw data or frequency data
- The raw data for each variable are in separate columns in the worksheet, and each observation is in a separate row. Multiple columns of data must all have the same number of observations.
- If you summarize the counts of data, you must have a column of frequencies. For more information, go to Comparison of summarized data, frequency data, and raw data.
- You can have quantitative data as well as categorical data
- A categorical variable has values that you can put into a countable number of categories or groups. In this analysis, categorical data are used for the table rows and columns.
- An associated variable (quantitative variable) has values that you can order, measure, and summarize using summary statistics. For more information, go to Comparison of categorical and quantitative variables.
- Missing categorical values are counted, but not included in the calculations
- By default, Minitab displays all missing values in your tables, but does not include them in the calculations unless you select Include displayed missing values in calculations in the Options sub-dialog box. When a data point is missing, by default, the entire row (observation) in the worksheet is omitted from the calculation.
- For more information, go to How to interpret missing values in a table.