... 5.1 Advantages and disadvantages of averages. Type of average Advantages Disadvantages Mean Uses all the data values Algebraically defined and so mathematically manageable Known sampling ... been tabulated (Appendix Al ,A4 ). The Standard Normal distribution has a mean of zero and a variance of one. If the random variable, x, has a Normal distribution with mean, p, and variance, ... the data, which may have major cost or time implications. Error checking Categorical data-It is relatively easy to check categori- cal data, as the responses for each variable can only take...