Why is this important?

2. Why is this important? • Requirement • Understand research articles • Do research for yourself • Real world

3. The Three Goals of this Course • 1) Teach “factoids” • 2) Teach a new way of thinking • 3) Self-Confidence in statistics

4. Statistics

5. Statistics Descriptive Statistics

7. Practice • Based on a sample of participants, it appears that a new drug will be effective at stopping headaches • The enrollment in this course as of December 15th was 22

8. Practice • On your first test you received a score of 84 out of 100 • Markey will likely be the next president; of the 100 people surveyed 82% said they would vote for him

9. Inferential Statistics • Problem: Is that going to be the exact answer? • Chance influences the sample • “true” variation • “error” variation • Sample = “true” + “error”

10. The meaning of numbers 90 • The number correct on a test out of 100 • The last two digits of your SSN • Your place in a race with 100 participants • Your place in the Boston Marathon • The percentile you scored on the GRE

11. Nominal Scale • Are not really scales at all • They do not scale items along any dimension, but rather label them • Numbers are used as names and have no quantitative value

12. Nominal Scales • Gender • Political party • Your SSN • Religion

13. Ordinal Scales • Has the characteristics of the nominal scale • PLUS: the characteristic of indicating greater than or less than • i.e., RANK ORDER

14. Ordinal Scales • Rank of professor • Your place in a foot race • Saying “This class is smaller then my other class”

15. Interval Scales • Has the properties of BOTH the nominal and ordinal scales • PLUS: the intervals between the numbers are equal • e.g., the distance between 4 and 5 is the same distance between 1 and 2

16. Interval Scales • Temperature • the difference between 10o F and 20o F is the same as the difference between 80o F and 90o F • Problem: What does 0o F mean? • With interval scales you CAN NOT make ratio statements

17. Interval Scale 50 70 10 30 80 0 20 40 60 Appears twice as large

18. Interval Scale 30 50 -10 10 0 60 -20 20 40 Now it appears three-times as large!

19. Ratio Scales • Has all the characteristics of the nominal, ordinal, and intervals scales • PLUS: it has a true zero point • This zero point indicates a complete absence of the thing measured

20. Ratio • Weight • Height • Speed • Distance

21. Features of the four scales

22. Why are the types of scales important? • They help you understand what type of statistic to use

23. Practice • Inches on a yardstick • Drivers licenses number • Dollars as a measure of income • Order of finish in a car race • Intelligence test scores

25. 1) Is depressed, blue 2) Is not relaxed, does not handle stress well 3) Can be tense

26. 4) Worries a lot 5) Is easily upset

27. Neuroticism Raw Score • Add your answers • Your score can range between 5- 25 • What does your score mean? • Note: It is meaningless unless you know how others scored

29. Simple Frequency Distribution 1) Find the highest and lowest scores 2) Write in descending order all the numbers from 24 to 6

30. Simple Frequency Distribution 3) Start with the number in the upper-left corner, draw a line under it, and place a tally mark in the frequency distribution 4) Do this with all the data 5) Count the number a tally marks

32. Group Frequency Distribution • Scores are grouped into equal-sized ranges called “class intervals” • Usually want around 10 class intervals

43. Dieting

44. Pornography

45. Prostitution

46. Mate Seeking

49. Graphic Presentation of Data • Basic parts of a graph Y axis X axis

50. Histogram • Graphs quantitative data • Neuroticism data