Table 1

Descriptive statistics

 Statistic Statistic Description of calculation Intent Measures of central tendency Mean Total of values divided by the number of values. Describe all responses with the average value. Median Arrange all values in order and determine the halfway point. Determine the middle value among all values, which is important when dealing with extreme outliers. Mode Examine all values and determine which one appears most frequently. Describe the most common value. Measures of variability Variance Calculate the difference of each value from the mean, square this difference score, sum all of the squared difference scores and divide by the number of values minus 1. Provide an indicator of spread. Standard deviation Square root of variance. Give an indicator of spread by reporting on average how much values differ from the mean. Range The difference between the maximum and minimum value. Give a very general indicator of spread. Frequencies Count the number of occurrences of each value. Provide a distribution of how many times each value occurs.