1. Political Science 30Political Inquiry Sections meet in Solis 105 this week.

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

3. Four Levels of Precision For Measuring Variables (Pollock, p.28) • 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.

4. Four Levels of Precision For Measuring Variables (Pollock, p.28) • 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.

5. Four Levels of Precision For Measuring Variables (Pollock, 28-29) • 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.

6. Four Levels of Precision For Measuring Variables • 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.

7. Kobe Bryant $24.8 million Pau Gasl $17.8 million Andrew Bynum $13.8 million Lamar Odom $8.2 million Ron Artest $6.3 million Luke Walton $5.3 million Steve Blake $4.0 million Derek Fisher $3.7 million Shannon Brown $2.2 million Matt Barnes $1.8 million Joe Smith $1.4 million Theo Ratliff $1.4 million Devin Ebanks $0.5 million Derek Caracter $0.5 million Measures of Central Tendency(Pollock, Ch. 2)

8. Measures of Central Tendency(Pollock, Ch. 2) • Mode: The most frequently occurring value. • $1.4 million and $0.5 million • 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. $3.85 million

9. Measures of Central Tendency • Mean is the arithmetic average of the values that all the cases take on. $6.6 million. • Add up all the values • Divide this sum by the number of cases, N.

10. Measures of Dispersion(Pollock, p.119-124) • 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. $53.8 million.

11. Measures of Dispersion(Pollock, pp. 119-124) • The standard deviation is the square root of the variance, $7.3 million.