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Introduction to Statistics for the Social SciencesSBS200, COMM200, GEOG200, PA200, POL200, or SOC200Lecture Section 001, Summer Session II, 20139:00 - 11:20am Monday - FridayRoom 312 Social Sciences (Monday – Thursdays)Room 480 Marshall Building (Fridays) Welcome http://www.youtube.com/watch?v=oSQJP40PcGI
Please click in Study Guide is online My last name starts with a letter somewhere between A. A – D B. E – L C. M – R D. S – Z Please double check All cell phones other electronic devices are turned off and stowed away
Homework due – Monday (July 22nd) • On class website: • Please print and complete homework worksheet #8 • Law of Large Numbers and Dan Gilbert
Schedule of readings Before Friday (July 19th) Please read chapters 3, 4, 5, & 6 in Ha & Ha Please read Chapters 10, 11, 12 and 14 in Plous Chapter 10: The Representativeness Heuristic Chapter 11: The Availability Heuristic Chapter 12: Probability and Risk Chapter 14: The Perception of Randomness
Use this as your study guide By the end of lecture today7/18/13 • Law of Large Numbers • Central Limit Theorem • Three propositions • True mean 2) Standard Error of Mean 3) Normal Shape • Calculating Confidence Intervals • Review for Exam 2
Homework review Based on data (Percent of stocks that meet reach or exceed target price on first day) Based on expert opinion - don’t have previous data for these two companies merging together Based on data (Percent of rockets that successfully launch) Based on apriori probability – not previous experience and not data-driven
Homework review Based on expert opinion (experience of experts), but not actual percent of space stations that have actually been critically damaged by debris. Based on actual data (percent of results that are fake pages)
. .8276 .1056 .2029 .1915 .3944 .4332 .3944 .3944 55 55 55 52 44 50 50 44 - 50 4 52 - 50 4 -1.5 +.5 = = 55 - 50 4 +1.25 = z of 1.5 = area of .4332 z of 1.5 = area of .1915 1.25 = area of .3944 55 - 50 4 55 - 50 4 +1.25 +1.25 = = .5000 - .3944 = .1056 z of 1.25 = area of .3944 z of 1.25 = area of .3944 .4332 +.3944 = .8276 .3944 -.1915 = .2029
.3264 Homework review .2152 .5143 .1255 .3888 .1736 .1736 .3888 3,000 3,500 2,500 3,500 3,000 2500 - 2708 650 3000 - 2708 650 3000 - 2708 650 -.32 = 0.45 0.45 = = z of -0.32 = area of .1255 z of 0.45 = area of .1736 z of 0.45 = area of .1736 3500 - 2708 650 3500 - 2708 650 1.22 = 1.22 = .5000 - .1736 = .3264 z of 1.22 = area of .3888 z of 1.22 = area of .3888 .3888 +.1255= .5143 .3888 - .1736 = .2152
.0764 Homework review .9236 .1185 .4236 .4236 .4236 .3051 10 12 20 20 10 - 15 3.5 -1.43 = 20 - 15 3.5 20 - 15 3.5 1.43 1.43 = = z of -1.43 = area of .4236 z of 1.43 = area of .4236 z of 1.43 = area of .4236 12 - 15 3.5 -0.86 = .5000 + .4236 = .9236 .5000 - .4236 = .0764 z of -.86 = area of .3051 .4236 – .3051 = .1185
Homework Worksheet: Confidence interval uses SEM
Homework Worksheet: Problem 1 29.2 Upper boundary raw score x = mean + (z)(standard deviation) x = 55 + (+ 2.58)(10) x = 80.8 80.8 Lower boundary raw score x = mean + (z)(standard deviation) x = 55 + (- 2.58)(10) x = 29.2 Standard deviation = 10 Mean = 55 2.58 sd 2.58 sd .99 55 ? ? 80.8 29.2
Homework Worksheet: Problem 1 29.2 Upper boundary raw score x = mean + (z)(standard error mean) x = 55 + (+ 2.58)(1.42) x = 58.7 80.8 51.3 58.7 Lower boundary raw score x = mean + (z)(standard error mean) x = 55 + (- 2.58)(1.42) x = 51.3 10 Standard deviation = 10 Mean = 55 49 1.42 2.58 sem 2.58 sem .99 55 ? ? 58.7 51.3
Homework Worksheet: Problem 5 29.2 80.8 51.3 58.7 10.2 29.8 8.02 8.6 9.18 16.9 23.1 4.09 13.11 8.02 9.18 2.67 7.8 7.8 8.6 9.4 14.5 9.4
How would you find the raw score for the 25th percentile Go to table .2500 nearest z = 0.67 x = mean + z σ .25 .25 z = -0.67
How would you find the raw score for the 75th percentile Go to table .2500 nearest z = 0.67 x = mean + z σ .50 .25 .25 z = +0.67
Variability and means Grades of all students in the class • 65 70 75 80 85 90 • Grades • Which is more variable? • Which has larger standard deviation • (dispersion, variance, range…?) Grades of “C” students What might the standard deviation be? What might this be an example of? • 65 70 75 80 85 90 • Grades Other examples? Notice: number lines equally spaced
Variability and means Remember, there is an implied axis measuring frequency f 60 65 70 75 80 85 90 f Remember to keep number lines equally spaced 60 65 70 75 80 85 90 Variable must be numeric
Variability and means Birth weight for infants From entire population 1 3 5 7 9 11 13 Birth weight in pounds Birth weight for infants from a “typical family” What might the standard deviation be? What might this be an example of? • 3 5 7 9 11 13 • Birth weight in pounds Other examples? Notice: number lines equally spaced
Variability and means Social distance norm(personal space) for international community 40 50 60 70 80 90 100Social Distance Norm Social distance norm (personal space) for Tucson What might the standard deviation be? What might this be an example of? 40 50 60 70 80 90 100 Social Distance Norm Other examples? Notice: number lines equally spaced
Variability and means Distributions same mean different variability Final exam scores “C” students versus whole class Birth weight within a typical family versus within the whole community Running speed 30 year olds vs. 20 – 40 year olds Number of violent crimes Milwaukee vs. whole Midwest Social distance (personal space) California vs international community
Variability and means Distributions different mean same variability Performance on a final exam Before versus after taking the class 40 50 60 70 80 90 100 Score on final (before taking class) 40 50 60 70 80 90 100 Score on final (before taking class) Notice: number lines equally spaced
Variability and means Distributions different mean same variability Height of men versus women 62 64 66 68 70 72 74 76Inches in height (women) 62 64 66 68 70 72 74 76Inches in height (men) Notice: number lines equally spaced
Variability and means Distributions different mean same variability Driving ability Talking on a cell phone or not 2 4 6 8 10 12 14 16Number of errors (not on phone) 2 4 6 8 10 12 14 16Number of errors (on phone) Notice: number lines equally spaced
Variability and means Comparing distributions different mean same variability Performance on a final exam Before versus after taking the class Height of men versus women Driving ability Talking on a cell phone or not Notice: number lines equally spaced
. Writing AssignmentComparing distributions (mean and variability) • Think of examples for these three situations • same mean but different variability • same variability but different means • same mean and same variability (different groups) • estimate standard deviation • calculate variance • for each curve find the raw score for the z’s given Remember: number lines equally spaced
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