The first order moment is the mean. MAD tells you how spread out from the mean your column of numbers is.The mode is the value that appears the most in the column. To test a statistical hypothesis, you take a sample, collect data, form a statistic, standardize it to form a test statistic (so it can be interpreted on a standard scale), and decide whether the test statistic refutes the claim. This statistic captures the amount of variability in the column.Variance measures how much a set of numbers is spread out. When you open the Real Statistics Examples Workbook for the first time you may receive the following messages: “This workbook contains links to other data sources” If you receive this message, click here to determine how to proceed. A convenience sample and voluntary response sample can be easy to perform, but these types of samples are not randomized to reduce or eliminate bias. Tip. It can also be used to compare measurements on different scales, since it effectively normalizes the scales of the numbers being compared. Three quarters of the values are less than or equal to the 75th percentile. Use technology and the given confidence level and sample data to find the confidence interval for the population mean .