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 Problem: What does 0o F mean?
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 20 40 60
Appears twice as large

18. Interval Scale 30 50
-10 10 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 What does your score mean?
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

42. Dieting

43. Pornography

44. Prostitution

45. Mate Seeking

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

48. Histogram
Graphs quantitative data
Neuroticism data

56. Graphing Data
Frequency distributions give exact values, but lack a visual summary of the data
Histographs provide a visual summary of the data, but lack exact values

57. Stem-and-Leaf Display
Provide both exact values and a visual summary of data

58. Stem-and-Leaf Separate each value into a “stem” and a “leaf”
Since we are using two digit numbers, the tens digit is the stem and the units digit is the leaf  
The number 12
Stem
Leaf 1 2

59. Stem-and-Leaf Display
Group the numbers with the same stems and list the stems in numerical order.  (If your leaf values are not in increasing order, order them now.)
Stem
Leaf 1 2
67899

60. Stem-and-Leaf Display
Stem-and-leaf display with a bigger data set
Note: The stem-and-leaf is like a histogram turned sideways!

62. Histogram

63. Frequency Polygon

64. Describing Distributions
Bell-shaped distribution

65. Describing Distributions

66. Describing Distributions

67. Kurtosis
The relative concentration of scores in the center of the distribution
Mesokurtic

68. Kurtosis
The relative concentration of scores in the center of the distribution
Platykurtic

69. Kurtosis
The relative concentration of scores in the center of the distribution
Leptokurtic

70. Practice
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