Data can be stacked, unstacked, or in a two-way table
For stacked data (One Y), you must have at least one column of numeric or date/time data, and two corresponding columns of categorical data. For unstacked data (Multiple Y’s), you must have multiple columns of numeric or date/time data, and each column is a group, and one corresponding column of categorical data. For data in a two-way table (Series in Rows or Columns), you must have multiple columns of numeric or date/time summary data. You can have a column of labels for the rows.
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.