Section 1.2 Part 2 AP Statistics September 11, 2008 Berkley High School, D1B1

AP Statistics, Section 1.2, Part 22 Describing with Numbers: Spread/Standard Deviation s 2 is called the variance, and its in units 2 s is called the standard deviation, and its in units.

AP Statistics, Section 1.2, Part 23 Describing with Numbers: Spread/Standard Deviation s measures spread about the mean and should be used only when the mean is chosen as the measure of center s equals 0 only when there is no spread. This happens only when all observations have the same value. s is not resistant. Outliers effect it adversely.

AP Statistics, Section 1.2, Part 24 Calculating s by hand Observation (x-bar) Deviation (x-sub-i – x-bar) Squared Deviation Sum = Mean = 1600

AP Statistics, Section 1.2, Part 25 Calculating s by hand Observation (x-bar) Deviation (x-sub-i – x-bar) Squared Deviation = = = = = = =-161 Sum = Mean = 1600 Sum = 0

AP Statistics, Section 1.2, Part 26 Calculating s by hand Observation (x-bar) Deviation (x-sub-i – x-bar) Squared Deviation = * 192 = = = = = = = Sum = Mean = 1600 Sum = 0Sum =

AP Statistics, Section 1.2, Part 27 Calculating s by hand

AP Statistics, Section 1.2, Part 28 Calculating s using TI-83

AP Statistics, Section 1.2, Part 29 Calculating s using TI-83

AP Statistics, Section 1.2, Part 210 Calculating s using TI-83

AP Statistics, Section 1.2, Part 211 Linear Transformations Adding “a” does not change the shape or spread Adding “a” does change the center by “a”

AP Statistics, Section 1.2, Part 212 Linear Transformations Multiplying by “b” does change the shape or spread by “b” Multiplying by “b” does change the center by “b”

AP Statistics, Section 1.2, Part 213 Assignment Exercises 1.40 – 1.47, The Practice of Statistics.