# Answers to Homework - Answers to Homework 8 pages 303-306#2(a b 3(a c 4 6(a c 7 8 11 14 17 18 20 21 24 2 a b The sample standard deviation

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Answers to Homework 8 2. a) The sample standard deviation describes the variability of the scores in the sample. In this case, the standard distance between a score and the sample mean is 12 points. b) The estimated standard error is 3 points. The standard error provides a measure of the standard distance between a sample mean and the population mean. 3. a) s 2 = SS/(n-1) = 1152/9-1 = 144 s M = √s 2 /n = 144/√9 = 4 c) s 2 = SS/(n-1) = 1260/36-1 = 36 s M = √s 2 /n = 36/√9 = 1 4. The sample variance in the t formula changes from one sample to another and contributes to the variability of the t statistics. A z-score uses the population variance which is constant from one sample to another. 6. a) t = ±2.306 c) t = ±2.064 7. a) 1 + 5 + 1 + 1 = 8/4 = 2 X X-M (X-M) 2 1 -1 1 5 3 9 1 -1 1 1 -1 1 12 SS / N-1 = variance √variance = SD 12/3 = 4 √4 =2 b) s M = √s 2 /n = 2/√4 = 1 8. a) 6 + 12 + 0 + 3 + 4 = 25/5 = 5

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## This note was uploaded on 01/15/2010 for the course PSYC 331 taught by Professor Dianealonso during the Fall '09 term at UMBC.

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Answers to Homework - Answers to Homework 8 pages 303-306#2(a b 3(a c 4 6(a c 7 8 11 14 17 18 20 21 24 2 a b The sample standard deviation

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