outlier is a value which looks isolated from other values, and it can be either upper or lower end.
A good stem and leaf plot
* shows the first digits of the number (thousands, hundreds or tens) as the stem and shows the last digit (ones) as the leaf.
* usually uses whole numbers. Anything that has a decimal point is rounded to the nearest whole number. For example, test results, speeds, heights, weights, etc.
* looks like a bar graph when it is turned on its side.
* shows how the data are spread—that is, highest number, lowest number, most common number and outliers (a number that lies outside the main group of numbers).