Statistics Cong Liu, Ph.D

Classes and Labs  Lecture –T, TR: 12:45-1:35  Lab Sections –T, TR: 1:45-3:45

Class Materials/Sources  Readings: –Course website Reading Assignments –Textbook (recommended): Frankfort-Nachmias, C. & Leon- Guerrero, A. (2009). Social Statistics for a diverse Society, 6 th edition. Pine Forge Press. –Textbook (recommended): Frankfort-Nachmias, C. & Leon- Guerrero, A. (2009). Social Statistics for a diverse Society, 6 th edition. Pine Forge Press.  Course website: –Syllabus –PowerPoint files –Lab materials and lab worksheets –Homework assignments –Project descriptions  Blackboard –Worksheet solutions (Under Course Document) –Homework solutions (Under Course Document) –Gradebook

Evaluation (Total = 1000 pts)  In class labs (21) 10 x 21 = 210 pts  Homework problems (12)10 x 12 = 120 pts  In-class Exercises (12 but only 10 count) 10 X 10 = 100 pts (12 but only 10 count) 10 X 10 = 100 pts  Project120 pts  Exams (4)100 X = 450 pts

Participation / Late Policy  Both class and lab participation are required  Labs: Clear with your lab instructor and submit the lab worksheet to Randi before the due date  Homework: Up to ½ credit (5/10)  In-class exercises: Clear with me before the class time  Projects: 10% penalty per day late  Exams: let me know 48 hours before the exam

Some Good Advice  Triple AAA –Attendance –Assignments –Answers of all questions:  Ask questions, especially during class time  Download and print out the PowerPoint file and bring it to class

Data Basics

Today’s Topics  What is scientific method? What is statistics?  What are variables?*  What are research designs?**

Ways of Knowing  Write down something that you know.  Write down how you know it.  Our focus: The Scientific method –The scientific method constitute data  Example: Movie ratings

Ways of Knowing  Our focus: The Scientific method –The scientific method constitute data  Example: Movie ratings –Statistics – a science of drawing conclusions from data  Example: Mean = 3.3/4 Stars

Variables: A characteristic that may change from one observation to another  Social class: Upper, middle, lower  Political party: Democrat, Republican  Population density: High, medium, low  Religion: Catholic, Protestant, Eastern Orthodox, Jewish, etc.  Number of siblings  Number of students in a class  % of female students at Hofstra  Time  Weight  Income in dollars  Education in total years of schooling

Independent and Dependent Variable  Insomnia problem: –Independent Variable (IV): The variable in a study that is manipulated by the researcher  Reading a book vs. not reading a book –“Assessment, Measurement, and Prediction for Personnel Decisions” –Don’t read a book –Dependent Variable (DV): The variable in a study that is measured by the researcher  How long it took me to fall into sleep

In-Class Exercises

Research Design  Experiment: Study a cause-and-effect relationship through manipulation of the independent variable while observing changes in the dependent variable –Insomnia problem: Comparing two conditions  Experimental condition  Control condition –Whether taking vitamin C supplements leads to fewer colds: Comparing two groups  Experimental group  Control group  Quasi-Experiment: Comparison of preexisting groups; the independent variables is a pre-existing characteristic (e.g., sex, age, etc.)

Research Design (Cont’d)  Survey: Researcher observes and measures variables of interest to find relationships between the variables –No attempt to manipulate the independent variable –Whether there is a relationship between SAT verbal scores and freshman GPAs

Recap: Lecture 1 – Data Basics  What is scientific method? What is statistics?  What are variables?* –Categorical variable and quantitative variable –Independent variable and dependent variable  What are research designs?** –Experiment –Quasi-experiment –Survey