These study tips are designed to clarify key points and help you to avoid errors that students commonly make. Review the Tips for Success as you study each chapter and review them again after you have studied each chapter.

1. One of the most common errors statistics students make when figuring the median is to forget to first line the scores up from lowest to highest
2. Always check that your deviation scores sum to zero.
• Many of the calculations in future chapters rely first on creating deviation scores, so be prepared to do this check lots of times!
3. Check that your calculations make intuitive sense.
• For example, if most of the scores in a distribution vary from 3 to 9, you should be surprised if you calculate the mean to be 14.53. Similarly, you should recheck your calculations if you calculate the standard deviation to be 19.28.
4. When calculating the variance and standard deviation, lay your working out as shown in the examples shown in the chapter (e.g., see Table 2-7, p. 64).
• While it might seem tedious to do this, it will help to ensure that you follow all of the steps and end up with the correct answer.
5. A common error when calculating the standard deviation is to jump straight from the sum of squared deviations (SS) to the standard deviation (by dividing by the number of scores, N).
• Remember, before finding the standard deviation, you must first calculate the variance (by dividing the sum of squared deviations by the number of scores). Take the square root of the variance to find the standard deviation.

Copyright © 1995-2008, Pearson Education, Inc., publishing as Pearson Prentice Hall Legal and Privacy Terms