Chapter 3 Notes (Part 1)

# Chapter 3 Notes (Part 1) - Review of Chapter 2 Range one...

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1 Review of Chapter 2 s Range : one measure of variability b Not used to calculate the variance s Calculating mean : (aka “the average”) the fulcrum around which all the other scores balance Review of Chapter 2 s Calculating the variance: s 1. find the mean s 2. subtract the mean from each score b This is the deviation score s 3. Square the deviation score s 4. Add the squared deviation scores b This is the Sums of Squares s 5. Divide the Sums of Squares by n-1 b “n” = the number of participants s **The range is not needed for these calculations Standard Deviation s *Not mentioned in Chapter 2* s Standard Deviation : the square root of the variance s If the mean and standard deviation of a normal distribution are known b it is possible to compute the percentile rank associated with any given score. b In a normal distribution, about 68% of the scores are within one standard deviation of the mean and about 95% of the scores are within two standards deviations of the mean

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2 Calculating Variance and the Standard Deviation Mean=5.6 -5.6^2=31.36 0-5.6=-5.6 0 5 4.4^2=19.36 10-5.6=4.4 10 4 3.4^2=11.56 9-5.6=3.4 9 3 -.6^2=.36 5-5.6=-.6 5 2 1.6^2=2.56 4-5.6=1.6 4 1 Squared Deviation Deviation Score Score Participant Calculating Variance and the Standard Deviation = 65.2 + 31.36 19.36 11.56 .36 2.56 Sum of Deviation score s
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## This note was uploaded on 04/14/2008 for the course PSYC 2094 taught by Professor Trcunningham during the Spring '07 term at Virginia Tech.

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Chapter 3 Notes (Part 1) - Review of Chapter 2 Range one...

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