1. Political Science 30 Political Inquiry
Sections meet in Sequoyah Hall 142 this week, hold off on downloading SPSS
Midterm study guide now posted
Office hours 11-1pm today
Political Science 30 Political Inquiry

2. Variables and their Values
You can think of any variable as a question:
What is the average lifespan in a country?
The potential values that the variable can take on are possible answers to that question:
45.9 years (Afghanistan)
71.1 years (The Bahamas)
50.2 years (Benin)
80.7 years (Japan)

3. Values that independent variables take on for different cases
IV #1 Wealth. Per capita GDP takes on different values in different countries.
Haiti $586
Cuba $3267
Spain $18,356
USA $39,678
IV #2 Health. Some countries have universal health care, some don’t.
Haiti, No
Cuba, Yes
Spain, Yes
USA, No

4. Measurement II. Quantifying and Describing Variables
Four Levels of Precision
Measures of Central Tendency
Mode
Median
Mean
Measures of Dispersion
Variance, Standard Deviation

5. Four Levels of Precision For Measuring Variables (Of Observations, p
Nominal Measure: You can put cases into a category, but cannot specify an order or relationship between the categories.
Example: The variable “religion” can take on values such as Catholic, Protestant, Mormon, Jewish, etc.

6. Four Levels of Precision For Measuring Variables (Of Observations, p
Ordinal Measure: You can put cases into different categories, and order the categories.
Example: The variable “strength of religious belief” can take on values such as devoutly religious, fairly religious, slightly religious, not religious.

7. Four Levels of Precision For Measuring Variables (Of Observations, p
Interval Measure: Not only can you order the categories of the variable, you can specify the difference between any two categories.
Example. The variable “temperature on the Fahrenheit scale” can take on values such as 32 degrees, 74 degrees, 116 degrees.

8. Four Levels of Precision For Measuring Variables (Of Observations, p
Ratio Measure: You can order categories, specify the difference between two categories, and the value of zero on the variable represents the absence of the variable.
Example. The variable “annual income” can take on the values of $0, $98,000, or $694,294,129.

9. Measures of Central Tendency (Of Observations, Chapter 3)
Kobe Bryant
$30,453,805
Nick Young
$1,106,942
Pau Gasol
$19,285,850
Jordan Farmar
Steve Nash
$9,300,500
Shawne Williams
Steve Blake
$4,000,000
Wesley Johnson
$916,099
Jordan Hill
$3,563,600
Xavier Henry
Chris Kaman
$3,183,000
Robert Sacre
$788,872
Jodie Meeks
$1,550,000
Kendall Marshall
$547,570
Ryan Kelly
$490,180

10. Measures of Central Tendency (Of Observations, Chapter 3)
Mode: The most frequently occurring value.
$1,106,942
Median: The midpoint of the distribution of cases.
1. Arrange cases in order
2. If the number of cases is odd, median is the value taken on by the case in the center of the list.
3. If the number of cases is even, median is the average of the two center values. $1,106,942

11. Measures of Central Tendency (Of Observations, p. 60)
Mean is the arithmetic average of the values that all the cases take on. $5,221,093
Add up all the values
Divide this sum by the number of cases, N.

12. Measures of Dispersion (Of Observations, p. 94)
The variance is a measure of how spread out cases are, calculated by:
Compute the distance from each case to the mean, then square that distance.
Find the sum of these squared distances, then divide it by N-1. ~$73 trillion.

13. Measures of Dispersion (Of Observations, p. 95)
The standard deviation is the square root of the variance, $8,555,409.