Introduction to Statistics for the Social Sciences
SBS200, COMM200, GEOG200, PA200, POL200, or SOC200
Lecture Section 001, Fall, 2014
Room 120 Integrated Learning Center (ILC)
10:00 - 10:50 Mondays, Wednesdays & Fridays.
http://www.youtube.com/watch?v=oSQJP40PcGI
Labs
Remember:
•
•
•
Bring electronic copy of your data
(flash drive or email it to yourself)
Your data should have correct formatting
See Lab Materials link on class website to doublecheck formatting of excel is exactly consistent
Schedule of readings
Before next exam (September 26th)
Please read chapters 1 - 4 in Ha & Ha 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
Reminder
Use this as your
study guide
By the end of lecture today
9/15/14
Correlational methodology
Positive, Negative and Zero correlation
Characteristics of a distribution
Central Tendency
Dispersion
Shape
Homework due – Wednesday (September 17th)
No new homework
– refine correlations worksheet
Review of
Homework Worksheet
Notice Gillian
asked 1300
people
.10 x 1,000,000 = 100,000
130/1300 = .10
.10
.08
.25
.35
.22
10
100,000
8
80,000
.10x100=10
25
250,000
35
350,000
22
220,000
130+104+325+455+286=1300
Review of
10
.10
Homework Worksheet
.08
8
.25
.35
.22
25
35
22
100,000
80,000
250,000
350,000
220,000
Review of
Homework Worksheet
Negative
Review
of
Down
-.9
Homework
Worksheet
Dollars Spent
Strong
9
8
7
6
5
4
3
2
1
10 20 30 40 50
Age
Strong
Negative
Down
Review
of
-0.9227
Homework Worksheet
=correl(A2:A11,B2:B11)
=-0.9226648007
Strong
Negative
Down
Review
of
-0.9227
Homework Worksheet
This shows a strong negative
relationship (r = - 0.92) between
the amount spent on snacks and
the age of the moviegoer
=correl(A2:A11,B2:B11)
=-0.9226648007
Description includes:
Both variables
Strength (weak,moderate,strong)
Direction (positive, negative)
Correlation r (actual number)
Scatterplot displays relationships between two
continuous variables
Correlation: Measure of how two variables co-occur and
also can be used for prediction
Range between -1 and +1
The closer to zero the weaker the relationship
and the worse the prediction
Positive or negative
Correlation
http://neyman.stat.uiuc.edu/~stat100/cuwu/Games.html
http://argyll.epsb.ca/jreed/math9/strand4/scatterPlot.htm
Correlation - How do numerical values change?
Let’s estimate the correlation coefficient for each of the following
r = +1.0
r = +.80
r = -1.0
r = -.50
r = 0.0
Positive correlation: as values on one variable go up,
so do values for other variable
Negative correlation: as values on one variable go up,
the values for other variable go down
Number of bathrooms in a city
and number of crimes committed
Positive correlation Positive correlation
Correlation does not imply causation
Is it possible that they are causally related?
Yes, but the correlational analysis does not answer that question
What if it’s a perfect correlation – isn’t that causal?
No, it feels more compelling, but is neutral about causality
Number of
Birthday Cakes
Linear vs curvilinear relationship
Linear relationship is a relationship
that can be described best with a
straight line
Curvilinear relationship is a
relationship that can be described
best with a curved line
This shows a strong positive
relationship (r = 0.97) between the
appraised price of the house and its
eventual sales price
r = +0.97
Description includes:
Both variables
Strength (weak,moderate,strong)
Direction (positive, negative)
Estimated value (actual number)
r = +0.97
r = -0.48
This shows a moderate negative
relationship (r = -0.48) between
the amount of pectin in orange
juice and its sweetness
Description includes:
Both variables
Strength (weak,moderate,strong)
Direction (positive, negative)
Estimated value (actual number)
Description includes:
Both variables
Strength (weak,moderate,strong)
Direction (positive, negative)
Estimated value (actual number)
r = -0.91
This shows a strong negative
relationship (r = -0.91) between
the distance that a golf ball is hit
and the accuracy of the drive
Description includes:
Both variables
Strength (weak,moderate,strong)
Direction (positive, negative)
Estimated value (actual number)
This shows a moderate positive
relationship (r = 0.61) between the
length of stay in a hospital and the
number of services provided
r = -0.91
r = 0.61
r = +0.97
r = -0.48
r = -0.91
r = 0.61
Both
Bothaxes
axes
have
real
and values
numbers
listed
are labeled
48 52 5660 64 68 72
Variable
name is listed
clearly
This shows the strong positive
(r = +0.8) relationship between the
heights of daughters (in inches) with
heights of their mothers (in inches).
48 52 56 60 64 68 72 76
Height of Daughters (inches)
Variable
name is listed
clearly
Description includes:
Both variables
Strength (weak,moderate,strong)
Direction (positive, negative)
Estimated value (actual number)
Both
Bothaxes
axes
have
real
and values
numbers
listed
are labeled
48 52 5660 64 68 72
Variable
name is listed
clearly
This shows the strong positive
(r = +0.8) relationship between the
heights of daughters (in inches) with
heights of their mothers (in inches).
48 52 56 60 64 68 72 76
Height of Daughters (inches)
Variable
name is listed
clearly
Description includes:
Both variables
Strength (weak,moderate,strong)
Direction (positive, negative)
Estimated value (actual number)
Both
Bothaxes
axes
have
real
and values
numbers
listed
are labeled
48 52 5660 64 68 72
Variable
name is listed
clearly
This shows the strong positive
(r = +0.8) relationship between the
heights of daughters (in inches) with
heights of their mothers (in inches).
48 52 56 60 64 68 72 76
Height of Daughters (inches)
Variable
name is listed
clearly
Description includes:
Both variables
Strength (weak,moderate,strong)
Direction (positive, negative)
Estimated value (actual number)
Both
Bothaxes
axes
have
real
and values
numbers
listed
are labeled
48 52 5660 64 68 72
Variable
name is listed
clearly
This shows the strong positive
(r = +0.8) relationship between the
heights of daughters (in inches) with
heights of their mothers (in inches).
48 52 56 60 64 68 72 76
Height of Daughters (inches)
Variable
name is listed
clearly
Description includes:
Both variables
Strength (weak,moderate,strong)
Direction (positive, negative)
Estimated value (actual number)
Both
Bothaxes
axes
have
real
and values
numbers
listed
are labeled
48 52 5660 64 68 72
Variable
name is listed
clearly
This shows the strong positive
(r = +0.8) relationship between the
heights of daughters (in inches) with
heights of their mothers (in inches).
48 52 56 60 64 68 72 76
Height of Daughters (inches)
Variable
name is listed
clearly
Description includes:
Both variables
Strength (weak,moderate,strong)
Direction (positive, negative)
Estimated value (actual number)
Break into groups of 2 or 3
Each person hand in own worksheet. Be sure to list your
name and names of all others in your group
Use examples that are different from those is lecture
1. Describe one positive correlation
Draw a scatterplot (label axes)
2. Describe one negative correlation
Draw a scatterplot (label axes)
3. Describe one zero correlation
Draw a scatterplot (label axes)
4. Describe one perfect correlation (positive or negative)
Draw a scatterplot (label axes)
5. Describe curvilinear relationship
Draw a scatterplot (label axes)
Both
Bothaxes
axes
have
real
and values
numbers
listed
are labeled
48 52 5660 64 68 72
Variable
name is listed
clearly
This shows the strong positive
(r = +0.8) relationship between the
heights of daughters (in inches) with
heights of their mothers (in inches).
48 52 56 60 64 68 72 76
Height of Daughters (inches)
Variable
name is listed
clearly
Description includes:
Both variables
Strength (weak,moderate,strong)
Direction (positive, negative)
Estimated value (actual number)
1. Describe one positive correlation
Draw a scatterplot (label axes)
2. Describe one negative correlation
Draw a scatterplot (label axes)
3. Describe one zero correlation
Draw a scatterplot (label axes)
4. Describe one perfect correlation (positive or negative)
Draw a scatterplot (label axes)
5. Describe curvilinear relationship
Draw a scatterplot (label axes)