1. Introduction to Statistics for the Social Sciences SBS200 - Lecture Section 001, Spring 2017 Room 150 Harvill Building 9:00 - 9:50 Mondays, Wednesdays & Fridays.
Welcome

2. Do not hand it in until it: Is correct, complete and stapled
Homework Assignment 7 & 8
Please complete the worksheet by hand
Please complete the memorandum
Due: Friday, February 6th
Do not hand it in until it:
Is correct, complete and stapled
If it is not complete and correct, consider this an “extension” and hand it in next time

3. Review of Homework Worksheet
Each of these are deviation scores
3 – 5 = -2
-22= 4
6 – 5 = +1 -2 1 3 -1 4 1 9
12= 1 3 -3 -1 1 9 1
Σ(x - µ) = 0 50 36 36 2
= 2
10 - 1
This is the standard deviation! 5 4
4.5 2 8 6

4. Review of Homework Worksheet
-12= 1
5 – 6 = -1 -1 2 3 1 4 9
22= 4
8 – 6 = +2 -1 3 1 -5 1 9 25 60 52 52
2.4
= 2.4
10 - 1 5 6
5.5 1 9 8

5. If it is complete and correct, hand it in now
Homework Assignment 7 & 8
Please complete the worksheet by hand
Please complete the memorandum
Due: Friday, February 6th
If it is complete and
correct, hand it
in now
Do not hand it in until it:
Is correct, complete and stapled
If it is not complete and correct, consider this an “extension” and hand it in next time

6. A note on doodling

7. Schedule of readings Before next exam (February 10)
Please read chapters in OpenStax textbook
Please read Appendix D, E & F online On syllabus this is referred to as online readings 1, 2 & 3
Please read Chapters 1, 5, 6 and 13 in Plous
Chapter 1: Selective Perception
Chapter 5: Plasticity
Chapter 6: Effects of Question Wording and Framing
Chapter 13: Anchoring and Adjustment

8. By the end of lecture today 2/1/17
Use this as your
study guide
By the end of lecture today 2/1/17
Measures of variability
Range
Standard deviation
Variance
Memorizing the four definitional formulae
z-scores

9. Lab sessions Everyone will want to be enrolled
in one of the lab sessions
Labs continue
next week

10. Writing Assignment
– Pop Quiz

11. Writing Assignment
– Pop Quiz

12. Writing Assignment – Pop Quiz Distance from the mean X Taller 2 inches
Preston is 2” taller than the mean (taller than most)
Taller
2 inches
Shorter X
Mike is 4” shorter than the mean (shorter than most)
Shorter
4 inches
Taller X
Equal to mean
Diallo is exactly same height as mean (half taller half shorter)
0 inches
Half are Shorter

13. Writing Assignment – Pop Quiz Sigma – standard deviation - population
Parameter
mu – a mean – an average - population
Parameter
x-bar – a mean – an average - sample
statistic
s – standard deviation - sample
statistic
The number of “standard deviations” the score is from the mean
population
Sigma squared and s squared - variance
Sigma is parameter (population) s is statistic (sample)
Deviation scores
(x-µ) for population (parameter) (x-x) is statistic (sample)
Sum of squares
On left is statistic on right is parameter
Standard deviation
s is statistic sigma is parameter
Degrees of freedom
sample

14. If it is complete and correct, hold on to it for your own reference

15. Summary of 7 facts to memorize

16. z score = raw score - mean standard deviation
If we go up one standard deviation
z score = +1.0 and raw score = 105
z = -1
z = +1
68%
If we go down one standard deviation
z score = -1.0 and raw score = 95
If we go up two standard deviations
z score = +2.0 and raw score = 110
z = -2
95%
z = +2
If we go down two standard deviations
z score = -2.0 and raw score = 90
If we go up three standard deviations
z score = +3.0 and raw score = 115
99.7%
z = -3
z = +3
If we go down three standard deviations
z score = -3.0 and raw score = 85
z score: A score that indicates how many standard deviations
an observation is above or below the mean of the distribution
z score = raw score - mean
standard deviation

17. Raw scores, z scores & probabilities
1 sd above and below mean
68%
z = +1
z = -1
Mean = 50
σ = 10
If we go up one standard deviation
z score = +1.0 and raw score = 60
If we go down one standard deviation
z score = -1.0 and raw score = 40

18. Raw scores, z scores & probabilities
2 sd above and below mean
95%
z = -2
z = +2
Mean = 50
σ = 10
If we go up two standard deviations
z score = +2.0 and raw score = 70
If we go down two standard deviations
z score = -2.0 and raw score = 30

19. Raw scores, z scores & probabilities
3 sd above and below mean
99.7%
z = +3
z = -3
Mean = 50
σ = 10
If we go up three standard deviations
z score = +3.0 and raw score = 80
If we go down three standard deviations
z score = -3.0 and raw score = 20

20. z score = raw score - mean standard deviation
If we go up one standard deviation
z score = +1.0 and raw score = 105
z = -1
z = +1
68%
If we go down one standard deviation
z score = -1.0 and raw score = 95
If we go up two standard deviations
z score = +2.0 and raw score = 110
z = -2
95%
z = +2
If we go down two standard deviations
z score = -2.0 and raw score = 90
If we go up three standard deviations
z score = +3.0 and raw score = 115
99.7%
z = -3
z = +3
If we go down three standard deviations
z score = -3.0 and raw score = 85
z score: A score that indicates how many standard deviations
an observation is above or below the mean of the distribution
z score = raw score - mean
standard deviation

22. Price per Movie Package
Movie Packages We sampled 100 movie theaters (Two tickets, large popcorn and 2 drinks)
What is the
most common
“deviation score”? 12
Deviation = 0 10
Frequency 8 6 4 2
Price per Movie Package
This distance is about
3 - 4 points on number line
What’s the ‘typical’ or standard deviation?
Mean = $37
Range = $27 - $47
Standard Deviation = 3.5

23. Amount of Bonuses (based on commission) We sampled 100 retail workers
68%
95%
99.7%
What’s the ‘typical’ or standard deviation?
This distance is about
10 points on number line
What’s the largest
possible deviations?
Mean = $50
Range = $25 - $75
$75 – $50= $25
$25 – $50= -$25
Standard Deviation = 10

24. Pounds of pressure to break
casing on an insulator (We applied pressure until the insulator casing broke)
What’s the ‘typical’ or standard deviation?
This distance is about
200 points on number line
Mean = 1700 pounds
Range = 1200 – 2100
What’s the largest
possible deviation?
= 400
Standard Deviation = 225
= -500

25. Waiting time for service at bank We sampled 100 banks (From time entering line to time reaching teller)
What’s the ‘typical’ or standard deviation?
This distance is about
Around .3 points on number line
Mean = 3 minutes
Range =
What’s the largest
possible deviation?
=.6
=-.6
Standard Deviation = 0.34

26. Number correct on exam (counted number of correct on 100 point test)
Mean = 50
Standard Deviation = 10

27. Quiz: Just for fun
Monthly electric bills for 50 apartments (amount of dollars charged for the month)
Mean = $150
Range =
The best estimate of the population standard deviation is
a. $150
b. $25
c. $50
d. $63
Standard Deviation = 25

28. Quiz: Just for fun
Amount of soda in 2-liter containers (measured amount of soda in 2-liter bottles)
What’s the largest
possible deviation?
Mean = 2.0
Range = 1.8 – 2.25
0.25
-0.20
The best estimate of the population standard deviation is
a. 0.1
b. 0.2
c. 0.3
d. 2.0
Standard Deviation = 0.1

29. Scores on an Art History exam (measured number correct out of 100)
Quiz: Just for fun
Scores on an Art History exam (measured number correct out of 100)
What’s the largest
possible deviation?
Mean = 50
Range =
= - 20
= 20
The best estimate of the population standard deviation is
a. 50
b. 25
c. 10
d. .5
Standard Deviation = 10

30. Scores on an Art History exam (measured number correct out of 100)
Quiz: Just for fun
Scores on an Art History exam (measured number correct out of 100)
Mean = 50
Range =
One way to estimate standard deviation*
σ≈ range / 5
Range 70 – 30 = 40
40 / 5 = 8
The best estimate of the population standard deviation is
a. 50
b. 25
c. 10
d. .5
Standard Deviation = 10

31. Scores, standard deviations, and probabilities
The normal curve always has the same shape.
They differ only by having different means and standard deviation

32. Thank you!
See you next time!!