1. Introduction to Statistics for the Social Sciences SBS200 - Lecture Section 001, Spring 2019 Room 150 Harvill Building 9:00 - 9:50 Mondays, Wednesdays & Fridays.
February 18

2. Even if you have not yet registered your clicker you can still participate
The
Green
Sheets

3. Before next exam (March 1st)
Schedule of readings
Before next exam (March 1st)
Please read chapters in OpenStax textbook
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

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

6. A word on “add-in”
Using Excel ?

7. t-tests
Using Excel

8. t-tests
Using Excel

13. Homework Assignment Worksheet
Distributed in Class
Interpreting t-tests

14. Whether or not feed had corn oil
No, feed had no corn oil
Yes, the feed had corn oil
Weight of eggs
60 grams if no corn oil
63 grams if corn oil
weight of eggs based on corn oil in food
weight of eggs based on corn oil in food
true experiment
between
nominal
ratio
200
100
100
198 99 99

15. -3.35
1.97
Yes
Yes
Yes
Yes
0.05
The weights of eggs for chickens who received the corn oil was 63
grams, while the weights of the eggs for chickens who did not receive
the corn oil was 60 grams. A t-test found this to be a significant
difference t(198) = -3.35; p < 0.05

16. Whether or not offered incentive
Was offered incentive
Was not offered incentive
Grade point average
2.3 for incentive group
2.1 for no incentive group
GPA based on incentive
GPA based on incentive
true experiment
between
nominal
interval
500
250
250
498
249
249

17. 3.64
1.964
Yes
Yes
Yes
Yes
0.05
The average GPA was 2.3 for students who were offered an incentive
and was 2.1 for students who were not offered an incentive.
A t-test was completed and we found this to be a significant
difference t(498) = 3.64; p < 0.05

18. Whether or not video included sound
Video with no sound
Video with sound
Number of items correctly recalled
3.7 for video with no sound
3.3 items for video with sound
number of items recalled
number of items recalled
true experiment
between
nominal
ratio 40 20 20 38 19 19

19. 1.17
2.02 No No No
0.248 No
0.05
The average number of items recalled was 3.7 for the students who
watched the ads with no sound, and was 3.3 for students who
watched video with sound. A t-test was completed and we found
no significant difference t(38) = 1.17; n.s.

20. Location of air conditioner plant
Japan
United States
Turnover rate
3.12% turnover rate for Japan
6.56% turnover rate for USA
turnover rates between Japan and USA
turnover rates between Japan and USA
quasi
between
nominal
ratio 10 5 5 8 4 4

21. -4.46
2.31
Yes
Yes
Yes
0.0021
Yes
0.05
The average turnover rate in the Japanese plants is 3.12 while the
average turnover rated in the American plants is A t-test
showed a significant difference, t(8) = ; p < 0.05

22. Always draw a picture!
Homework worksheet

23. 1 .6800 1 sd 1 sd 28 30 32 Homework worksheet .6800 also fine: 68%
z =-1
z = 1 28 30 32

24. 2 .9500 2 sd 2 sd 26 28 30 32 34 Homework worksheet .9500
also fine: %
also fine:
.9500
2 sd
2 sd
z =-2
z = 2 26 28 30 32 34

25. 3 .9970 3 sd 3 sd 24 26 28 30 32 34 36 Homework worksheet .9970
also fine: %
also fine:
.9970
3 sd
3 sd
z =-3
z = 3 24 26 28 30 32 34 36

26. 4 .5000 24 26 28 30 32 34 36 Homework worksheet .5000 also fine: 50%
z = 0 24 26 28 30 32 34 36

27. 5 .4332 24 26 28 30 32 34 36 Homework worksheet z = 33-30 z = 1.5
Go to
table
.4332 2 5
also fine: %
.4332
z = 1.5 24 26 28 30 32 34 36

28. z =
33-30 2
z = 1.5
Go to
table
.4332
Add area
Lower half
= .9332 6
also fine: %
.9332
.4332
.5000
z = 1.5 24 26 28 30 32 34 36

29. 7 .4332 .0668 24 26 28 30 32 34 36 Homework worksheet z = 33-30 = 1.5
= 1.5
Go to
table
.4332
Subtract
from .5000
= .0668 2 7
also fine: 6.68%
.4332
.0668
z = 1.5 24 26 28 30 32 34 36

30. z =
29-30 2
= -.5
Go to
table
.1915
Add to upper
Half of curve
= .6915 8
also fine: %
.6915
.1915
.5000
z = -.5 24 26 28 30 32 34 36

31. =
25-30 2
= -2.5
.4938
Go to table =
31-30 2
=.5
.1915
Go to table
= .6853 9
also fine: %
.6853
.1915
.4938
z =-2.5
z = .5 24 26 28 30 32 34 36

32. z =
27-30 2
= -1.5
Go to
table
.4332
Subtract
From .5000
= .0668 10
also fine: 6.68%
.5000
.0668
.4332
z =-1.5 24 26 28 30 32 34 36

33. z =
25-30 2
= -2.5
Go to
table
.4938
Add lower
Half of curve
= .9938 11
also fine: %
.9938
.5000
.4938
z =-2.5 24 26 28 30 32 34 36

34. z =
32-30 2
= 1.0
Go to
table
.3413
Subtract
from .5000
= .1587 12
.5000
also fine: %
.1587
.3413
z =1 24 26 28 30 32 34 36

35. 13 24 26 28 30 32 34 36 50th percentile = median 30 In a normal curve
Median= Mean = Mode
z =0 24 26 28 30 32 34 36

36. 28 32 14
.6800
1 sd
1 sd
z =-1
z = 1 24 26 28 30 32 34 36

37. z table provides area from mean to score
x = mean + z σ = 30 + (.74)(2) = 31.48
77th percentile
Find area
of interest
= .2700
Find nearest z = .74 15
.2700
.7700
z table provides area from mean to score
.5000
31.48
z =.74 24 ? 30 36

38. z table provides area from mean to score
13th percentile
Find area
of interest
= .3700
Find nearest z = -1.13
x = mean + z σ = 30 + (-1.13)(2) = 27.74 16
Note:
=.50
z table provides area from mean to score
.3700
.1300
z =-1.13
27.74 ? 24 30 36

39. Please use the following distribution with
a mean of 200 and a standard deviation of 40. 80
120
160
200
240
280
320

40. .6800 17
also fine: %
also fine:
.6800
1 sd
1 sd
z =-1
z = 1
160
200
240

41. .9500 18
also fine: %
also fine:
.9500
2 sd
2 sd
z =-2
z = 2
120
200
280

42. 19 .9970 3 sd 3 sd 80 200 320 .9970 also fine: 99.70% also fine: .9974
z =-3
z = 3 80
200
320

43.
Go to
table =
= .75
.2734 40 20
also fine: %
.2734
z =.75 80
120
160
200
240
280
320

44. Go to
table
Subtract
from .5000
z = 40
= -.25
.0987
= .4013 21
also fine:
.0987
.4013
.5000
z =-.25 80
120
160
200
240
280
320

45. Go to
table
Add to upper
Half of curve
z = 40
= -.5
.1915
= .6915 22
also fine: %
.5000
.1915
.6915
z =-.5 80
120
160
200
240
280
320

46. z = 40
= 0.9
Go to
table
.3159
Subtract
from .5000
= .1841 23
.3159
also fine: %
.1841
z =.9 80
120
160
200
240
280
320

47. z = 40
= -.2
.0793
Go to table
= .2881
z = 40
=.55
.2088
Go to table 24
also fine: %
.2881
.2088
.0793
z =-.2
z =.55 80
120
160
200
240
280
320

48. = .9693
z =
= 1.875
Go to
table
Add area
Lower half
.4693 or
.4699
= .9699 40 25
Please note:
If z-score rounded to 1.88,
then percentile = 96.99%
also fine: %
.9693
.4693
.5000
z =1.875 80
120
160
200
240
280
320

49. Add area
Lower half
= .0089
= .0087
z = 40
z = 2.375
Go to
table
.4911 or
.4913 26
Please note:
If z-score rounded to 2.38,
then area = .0087
also fine: 0.89%
.4911
.0089
z =2.375 80
120
160
200
240
280
320

50. z = 40
= -1.75
.4599
Add to upper
Half of curve
Go to
table
= .9599 27
also fine: %
.9599
.5000
.4599
z =-1.75 80
120
160
200
240
280
320

51. 40
z =
= -1.75
.4599
Subtract
from .5000
= .0401
Go to
table 28
.0401
.4599
.5000
also fine: 4.01%
z =-1.75 80
120
160
200
240
280
320

52. z table provides area from mean to score
x = mean + z σ = (2.33)(40) = 293.2
99th percentile
Find area
of interest
= .4900
Find nearest z = 2.33 29
.4900
.9900
z table provides area from mean to score
.5000
293.2
z =2.33 80 ?
120
160
200
240

53. z table provides area from mean to score
33rd percentile
Find area
of interest
= .1700
Find nearest z = -.44
x = mean + z σ = (-.44)(40) = 182.4 30
z table provides area from mean to score
Note:
=.50
.3300
.1700
182.4
z =-.44 ? 80
200
240
280
320

54. z table provides area from mean to score
40th percentile
Find area
of interest
= .1000
Find nearest z = -.25
x = mean + z σ = (-.25)(40) = 190 31
z table provides area from mean to score
Note:
=.50
182.4
.1000
.4000
z =-.25 ? 80
200
240
280
320

55. z table provides area from mean to score
67th percentile
Find area
of interest
= .1700
Find nearest z = .44
x = mean + z σ = (.44)(40) = 217.6 32
z table provides area from mean to score
.1700
z =.44 80
200
217.6 ?
320

56. Thank you!
See you next time!!