Introduction to Statistics for the Social Sciences SBS200, COMM200, GEOG200, PA200, POL200, or SOC200 Lecture Section 001, Spring 2015 Room 150 Harvill Building 8:00 - 8:50 Mondays, Wednesdays & Fridays.

Instructor:Suzanne Delaney, Ph.D. Office:405 “N” McClelland Hall Phone: Office hours:12:00 – 1:30 Monday and Friday and by appointment Introduction to Statistics in the Social Sciences

Schedule of readings Before next exam (February 13 th ) Please read chapters 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

Everyone will want to be enrolled in one of the lab sessions Labs start next week

Homework due Assignment 2 Independent and Dependent Variables Due: Monday, January 26 th

Register clickers soon and receive extra credit! (By January 28th)

Measurement: observable actions Theoretical constructs: concepts (like “humor” or “satisfaction”) So far, Operational definitions Validity and reliability Independent and dependent variable Random assignment and Random sampling

Within - participant (same as within - subject) & Between - participant (same as between - subject) Music make plants grow? Within-participant design: each subject participates in every level of independent variable (aka repeated measures) Animals make funnier commercials? Effect of sleep on memory ability Between-participant design: each subject participates in only one level of independent variable Within or between participant design?

If you want to know if studying improves test performance in young children Break up group of kids into two groups Group 1 - studies & tested Group 2 - does not study & tested What is the independent variable? Is this a “quasi” or “true” experiment? “Between” or “within” participant design? How many levels are there of the IV? What is the dependent variable?

If you want to know if “Ginseng drink” is associated with feelings of satisfaction What is the independent variable? “Between” or “within” participant design? What is the dependent variable? First test group with placebo drink (sugar pill) Then test same group with “Ginseng drink” Placebo How many levels are there of the IV?

Placebo (single blind) versus double blind procedure Single blind procedure (example: use of placebo) Double blind procedure What about experimenter bias?

Duration Distance to the moon Number of kids in classroom Height Number of eggs in a carton Number of textbooks required for class Amount of sand Grains of sand Number of cookies on a plate Amount of milk in a glass Continuous versus discrete Continuous variable: Variables that can assume any value. There are (in principle) an infinite number of values between any two numbers Discrete variable: Variables that can only assume whole numbers. There are no intermediate values between the whole numbers

Categorical data (also called qualitative data) - a set of observations where any single observation is a word or a number that represents a class or category Categorical versus Numerical data Numerical data (also called quantitative data) - a set of observations where any single observation is a number that represents an amount or count

Gender - male or female Handedness - right handed or left handed Family size Ethnic group Temperature (Fahrenheit) Age (Time since birth) Yearly salary Hair color GPA Breed of dog Categorical data (also called qualitative data) - a set of observations where any single observation is a word or a number that represents a class or category Numerical data (also called quantitative data) - a set of observations where any single observation is a number that represents an amount or count Please note this is a binary variable Temperature (Kelvin)

What are the four “levels of measurement”? Nominal Ordinal Interval Ratio Names Categories Least numeric Weakest Names Categories Intrinsic ordering Approaching Numeric Categories Intrinsic ordering Equal sized intervals Units meaningful Most numeric Absolute zero

What are the four “levels of measurement”? Interval data - measurable differences in amount, equal intervals Ordinal data - order, rankings, differences in degree Ratio data - measurable differences in amount with a “true zero” Nominal data - classification, differences in kind, names of categories Gender - male or female Handedness - right handed or left handed Family size Jersey number Place in a foot race (1 st, 2 nd, 3 rd, etc) Categorical data Numerical data

What are the four “levels of measurement”? Interval data - measurable differences in amount, equal intervals Ordinal data - order, rankings, differences in degree Ratio data - measurable differences in amount with a “true zero” Nominal data - classification, differences in kind, names of categories Ethnic group Temperature Age Yearly salary Hair color Breed of dog Telephone number Categorical data Numerical data

Please note : page 29 in text

Question 1 - Population: The entire group of people we want to know about - Sample: The subgroup of people who actually participate in a research study (so we can better understand whole population) Assignment 1 – Chapter 2 Questions 1, 3-7, 9, 10, Question 3 - Dependent variable: The variable being measured by investigator. The data that is being recorded. - Independent variable: The factor that is being manipulated (or compared) by the experimenter. The data: what are you measuring How do your groups differ Question 4 - Statistic: number gathered from a sample - Parameter: number gathered from a population (or is estimated from sample statistic) Question 5 - Discrete: measurements with only whole numbers* - Continuous: possibly infinite number of values between two measurements (e.g. height, weight, and duration)

Question 6 - Descriptive: Measurements from whole group you are describing. - Inferential: Measurements of whole group based on subset of the group you are describing, requires inferences about people not actually measured Assignment 1 – Chapter 2 Questions 1, 3-7, 9, 10, Question 7 - Random Sampling: Everyone in population has same chance to be chosen into the sample – sample should reflect population Note: This is different from random assignment, which determines “true” vs “quasi” experiments

Question 9 - Does amount of sleep (4 vs 8 hours) affect class attendance? Selected 350 students from 38,000 undergraduates at U of Washington and randomly assigned students into two groups. Group 1 gets 4 hours sleep What is the independent variable? How many levels are there of the IV? Group 2 gets 8 hours sleep -Amount of sleep -2 levels (4 hours vs 8 hours) What is the dependent variable? What is population and sample? -Class attendance -Population: whole school -Sample: group of 350 students What is statistic ? -Average class attendance for 350 students Note: Parameter would be what we are guessing for the whole school based on these 350 students Quasi versus true experiment (random assignment)? -True Random sample? -Doesn’t say in the problem, so we have to assume “no”

Question 10 - Does gender of the teacher affect test scores for the students in California? Selected 150 students from Santa Monica and created two groups. Group 1 gets a female teacher What is the independent variable? How many levels are there of the IV? Group 2 gets a male teacher -Gender of teacher -2 levels (male vs female teacher) What is the dependent variable? What is population and sample? -Test Scores -Population: California -Sample: group of 150 students from Santa Monica What is statistic ? -Average test score for 150 students Quasi versus true experiment (random assignment)? -Doesn’t say in the problem, so we have to assume “no” Random sample? -No – Random sample would require that everyone in California be equally likely to be chosen.

Question 15: What is level of measurement for “brand of shoes”? -Nominal Question 16: What is level of measurement for “temperature”? -Kelvin is ratio -Fahrenheit is interval Question 17: What is level of measurement for ___ -time to finish a race is ratio -1 – 7 ranking is interval -types of drinks is nominal -level of confidence is ordinal -E.g. Not confident – a little confident – very confident

Question 18: a.How many numbers do we have? Find “N” N = 7 x 1 = 72 x 2 = 29 x 3 = 10 x 4 = 49 x 5 = 22 x 6 = 58 x 7 = 63 x 1 = 72 x 2 = 29 x 3 = 10 x 4 = 49 x 5 = 22 x 6 = 58 x 7 = 63 b. What do we get if we add up all the numbers? Find Σx Σx = 303 c. What do we get if we square each number then add them up? Find Σx 2 Σx = 16,343 d. What do we get if add up the numbers then square it? Find ( Σx) 2 Σx = 91,809 e. What do we get if we subtract 6 from each number then add them up? Find Σ(x - 6) Σ(x - 6) = 261 f. What do we get if we add up the numbers then add 12? Find Σx + 12 Find Σx + 12 = 315

Question 19: What is level of measurement for “time to react”? -Ratio Question 20: What is level of measurement for “level of anxiety”? -Ordinal or Interval or Ratio Question 21: What is level of measurement for “math ability”? -Ratio Question 22: What is level of measurement for “Fahrenheit”? -Interval Question 23: What is level of measurement for “birth weight”? -Ratio Question 24: What is level of measurement for “sex of child”? -Nominal Question 25: What is level of measurement for “number of students”? -Nominal “number of students”? - ratio “ranking of beauty”? - ordinal “ranking of poems”? - ordinal “anxiety level”? – ordinal, interval or ratio