... statisticsµ Mean of a populationσ Standard deviation of a populationσ2Variance of a populationΠ Proportion of a populationx Mean of a samples Standard deviation of a samples2Variance of a samplen ... appropriate for this type of data, and many tech-niques covered in Chapter 11, on nonparametric statistics, are also appropriate forcategorical data.When data can take on only two values, as in ... thischapter, and others are covered in Chapter 11.Interval DataInterval data has a meaningful order and also has the quality that equal intervalsbetween measurements represent equal changes...