1. Sociology 601: Class 1, September 1 2009 Syllabus Course website Objectives Prerequisites Text Homeworks Class time Exams Grading Schedule

2. Sociology 601: Class 1, September 1 2009 Basic Terms –Statistical inference (Chapter 1.1 to 1.2) –Variables and scales (Chapter 2.1) –Randomization (2.2) –Sampling and non-sampling variability (2.3) –Sampling techniques (2.4)

3. Chapter 1.1 – 1.2 definitions (pages 3-5) Descriptive Statistics: summary descriptions of a collection of data Statistical Inferences: predictions or generalizations made from data Sample: subset of the population on which the study collects data Population: total set of subjects of interest in a study Statistic: a numerical summary of sample data Parameter: a numerical summary of a population

4. Choosing a Population: an example The student government at the University of Maryland conducts a study about alcohol abuse among students. One hundred of the 33,000 members of the student body are sampled and asked to complete a questionnaire. One question is “On how many days in the past week did you consume at least one alcoholic drink?” Q: What is the population of interest?

5. Populations People in the United States Countries, cities, census tracts Years Newspaper stories or TV shows Organizations, social movements Mixed: people over time

6. Chapter 2.1 definitions (pages 12-17) variable : a characteristic that can vary among subjects in a population –race, age, sex, educational attainment –Q: is a characteristic a variable if it is fixed for an individual? (e.g. race) constant : a characteristic that cannot vary among subjects in a population –One constant is the quality of being a member of the population (duh! - yet statistically important)

7. Chapter 2.1, Scales (pages 12-17) Nominal scale: unordered, discrete categories, –(religious affiliation, vote) Ordinal scale: naturally ordered, discrete categories –(social class -- upper, middle, lower) Interval scale: variables whose values have a specific distance from one another. –(income is a continuous variable with an interval scale) –(number of times married is a discrete variable with an interval scale)

8. Dichotomous Variables Any variable with only two categories Examples: gender Examples: Catholic Examples: Middle class Examples: Family income > $100K Q: Nominal, Ordinal, or Interval?

9. Chapter 2.1, useless definitions (pages 12-17) Qualitative variables: = nominal scale of measurement. Quantitative variables: = interval scale of measurement. Categorical variables: includes all variables with nominal or ordinal scales

10. Practice with variable scales Case id Education: years completed Education level (1 = < high school grad, 2 = high school or some college, 3 = four or more years of college Does r have less than a high school education? (1 = yes, 0 = no) Does r have a high school education, but less than 4 years of college? (1 = yes, 0 = no) Does r have 4 or more years of college? (1 = yes, 0 = no) 1 12 2 9 3 13 4 11 5 14 6 19 7 12 8 16 9 15

11. Practice with variable scales Case id Education: years completed Education level (1 = < high school grad, 2 = high school or some college, 3 = four or more years of college Does r have less than a high school education? (1 = yes, 0 = no) Does r have a high school education, but less than 4 years of college? (1 = yes, 0 = no) Does r have 4 or more years of college? (1 = yes, 0 = no) 1 122010 2 91100 3 132010 4 111100 5 142010 6 193001 7 122010 8 163001 9 152010 mean 13.442.000.220.560.22