The Children's Depression Inventory (CDI), Developed from Beck's Depression Inventory

Short Answer

The Children's Depression Inventory (CDI), developed from Beck's Depression Inventory is a self-report instrument with 27 sets of statements. Higher scores indicate higher levels of depression. Scores above 13 are said to indicate a Major Depressive Disorder (MDD) and few false positives have been reported. A random sample of 20 fifth grade students was selected and given the test. Their scores were as follows: 9,10,11,9,8,9,17,2,7,11,6,12,9,10,9,9,8,10,14,1.
-Find the standard deviation for the group.