PSYC 2002 Lecture Notes - Lecture 4: Squared Deviations From The Mean, Variance, Xm Satellite Radio

• School: Carleton University
• Department: Psychology
• Course: PSYC 2002
• Professor: Steven Carroll

Document Summary

The spread of scores in a distribution. The extent to which the scores in a distribution differ from one another. What is the mean of this distribution: answer: 50. Imagine these data represent scores on a test. But the class average was 50 doesn"t tell the whole story. Only one person actually got a score of 50 on the test. Calculate the amount that each student"s score deviated from the class mean. Except, in this case, we"re using ( x - ) instead of x. ( x - ) = 0. We now have no way to calculate the average amount that scores deviate from the mean! The problem is this: the negative deviations are always going to cancel-out the positive deviations. Another way to write (x - ) is ss , which stands for sum of the squared deviations . But hang on a second (x m)2. The original range of scores went from 10 to 90.