Table 1

Descriptive statistics

StatisticStatisticDescription of calculationIntent
Measures of central tendencyMeanTotal of values divided by the number of values.Describe all responses with the average value.
MedianArrange all values in order and determine the halfway point.Determine the middle value among all values, which is important when dealing with extreme outliers.
ModeExamine all values and determine which one appears most frequently.Describe the most common value.
Measures of variabilityVarianceCalculate 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 deviationSquare root of variance.Give an indicator of spread by reporting on average how much values differ from the mean.
RangeThe difference between the maximum and minimum value.Give a very general indicator of spread.
FrequenciesCount the number of occurrences of each value.Provide a distribution of how many times each value occurs.