1. Psych 2 – Statistical Methods for Psychology and Social Science
G. W. Gibson, phd, lmft

2. Every individual is an exception to the rule.
Carl Jung

3. Psych 2: Statistical Methods
Unit
1: Introduction to Statistics
2: Descriptive Statistics
3: Probability
4: Inferential Statistics
5: T Test & ANOVA
6: Chi-square

4. Unit 1: Introduction to Statistics

5. Unit 1: Introduction to Statistics
1.1 Definition
1.2 Groups
1.3 Scales of Measurement
1.4 Frequency Distribution
1.5 Algebra Review

6. 1.1 Definition
Statistics: Statistics is the science of data. It involves collecting, classifying, analyzing, interpreting, and presenting numerical information.

7. Descriptive Statistics Inferential Statistics
1.1 Definition
Types of Statistics
Descriptive Statistics
Inferential Statistics

8. 1.1 Definition Descriptive Statistics
A descriptive statistic is a statistic that summarizes and describes a set of data.
Examples are frequencies, percentages, means, and medians.

9. 1.1 Definition Inferential Statistics
An inferential statistic is a statistic that indicates how much confidence we can have in generalizing results from a sample to a population.
Examples are correlation tests, t tests, analysis of variance tests, and Chi-square tests.

10. 1.1 Definition

11. 1.2 Groups
Types of Groups
Population
Sample

12. 1.2 Groups
Population
A population is a group in which a researcher is interested. A population can be quite small or can be extremely large in size. There is no so-called minimum number of people in a population.

13. 1.2 Groups
Population
All members
of the group.

14. 1.2 Groups
Sample
A sample is a group selected from a population. A sample should represent the population from which it was chosen, as much as possible.

15. 1.2 Groups
Sample
Some members
of the group.

16. 1.2 Groups
The sample is
taken from the
population.

17. 1.2 Groups

18. 1.2 Groups
Group Description
Parameter
Statistic

19. 1.2 Groups
Parameter
A Parameter is a description of people in a Population.

20. 1.2 Groups
Statistic
A Statistic is a description of people in a Sample.

21. 1.3 Scales of Measurement Scales of Measurement Categorical Numerical
Nominal
Ordinal
Interval
Ratio

22. 1.3 Scales of Measurement Nominal A nominal scale involves categories.
Nominal scale questions typically require word answers.

23. 1.3 Scales of Measurement
Nominal
Sex:
Male or Female

24. 1.3 Scales of Measurement Nominal Race/ethnicity: Asian, Black,
Hawaiian/
Pacific Islander, Native American,
White, Hispanic
or Latino

25. 1.3 Scales of Measurement Nominal Political Party: Republican,
Democrat,
Independent,
Libertarian

26. 1.3 Scales of Measurement Ordinal
An ordinal scale involves categories that have order or hierarchy.
Ordinal values are like nominal values, but with order.

27. 1.3 Scales of Measurement Ordinal Military Rank: Private Corporal
Sergeant
Master Sergeant

28. 1.3 Scales of Measurement Ordinal Grade Level: Freshman Sophomore
Junior
Senior

29. 1.3 Scales of Measurement
Ordinal
Mood: Happy, euthymic, sad

30. 1.3 Scales of Measurement Interval
An interval scale has an equal distance between 'points' or values and no meaningful zero point or value.
Interval scale questions require numerical answers.

31. 1.3 Scales of Measurement Interval Temperature: Equal distance
between degrees,
but no meaningful zero

32. 1.3 Scales of Measurement
Interval
IQ & SAT
scores

33. 1.3 Scales of Measurement Ratio
A ratio scale has an equal distance between values and a meaningful zero point.
Ratio scale questions require numerical answers.

34. 1.3 Scales of Measurement
Ratio
Age

35. 1.3 Scales of Measurement
Ratio
Weight

36. 1.3 Scales of Measurement Summary ü Characteristic Nominal Ordinal
Interval
Ratio
Counts ü
Ordered
Equal distance
between values
Meaningful zero

37. 1.4 Frequency Distribution
Number of Cases
Frequency
Percentage

38. 1.4 Frequency Distribution
A frequency refers to the number cases (e.g. people) with a certain “characteristic” or the number cases who obtained a certain score or score interval.

39. 1.4 Frequency Distribution
Four out of five dentists, or
800 out of 1000 dentists
recommend toothbrushes.

40. 1.4 Frequency Distribution
Percentage
A percentage (or relative frequency) refers to the number cases (e.g. people) per 100 cases, with a certain “characteristic” or who obtained a certain score or score interval.

41. 1.4 Frequency Distribution
Percentage
4/5 = 80/100 = 80%
= 80%
40 

42. 1.4 Frequency Distribution
Cumulative Frequency
A cumulative frequency refers to the number of cases (e.g. people) who scored at or below a given score or score interval (or category).

43. 1.4 Frequency Distribution
Cumulative Percentage
A cumulative percentage refers to the percentage of cases (e.g. people) who scored at or below a given score or score or score interval. A cumulative percentage is related to a percentile rank.

44. 1.4 Frequency Distribution
A frequency distribution shows how many individuals received each score or scored in each score interval.

45. 1.4 Frequency Distribution
Scores
Frequency
90-100 2
80-89 4
70-79 8
60-69
50-59 3
Coin Toss
Frequency
Heads 53
Tails 47

46. 1.4 Frequency Distributionx f cf %
cum%
20 – 24 2 20 10
100
15 – 19 5 18 25 90
10 – 14 9 13 45 65
5 – 10 4
0 – 4

47. 1.4 Frequency Distribution
Class Rules Regarding Frequency Distribution:
1.4.1 Higher scores or score intervals are placed on top, and lower scores or score intervals are placed on the bottom.
1.4.2 Cummulative frequency and cumulative percentages are calculated from the bottom to the top.

48. 1.4 Frequency Distribution
Class Rules Regarding Frequency Distribution:
1.4.3 The number at the top of cumulative frequency will equal the total number of observations.
1.4.4 The number at the top of cumulative percentage will be 100%, or near 100% due to rounding.

49. 1.4 Frequency Distribution
Class Rules Regarding Frequency Distribution:
1.4.5 The lowest and highest score or score interval must have a frequency other than zero.
1.4.6 All possible scores or score intervals between the lowest and highest must be listed.

50. 1.5 Algebra Review Basic Algebra
Add, subtract, multiply, divide, square, square root.
Order of operation (PEMDAS)
For this class, round off to two decimals places.

51. 1.5 Algebra Review Basic Algebra: Multiplication and Exponents
Exponets: = 5 × 5 × 5 = 125
* 5×3 = is five 3’s = = 15, but three 5’s look better above.

52. 1.5 Algebra Review Basic Algebra: Squares
To square a number is to multiply the number by itself.
42 = 4 × 4 = = 25
72 = 7 × 7 = = 64

53. 1.5 Algebra Review Basic Algebra: Order of Operation
Left to right: × 3
6 × 3 = 18
Multiplication: × 3
= 14
Order matters:
2 + 4 • 3

54. 1.5 Algebra Review
Basic Algebra: Order of Operation

55. Multiplication Division (left to right)
1.5 Algebra Review
Basic Algebra:
Order of Operation
“PEMDAS”
Pudgy Elves Might Demand A Snack!
Parentheses
Exponents and Roots
Multiplication Division (left to right)
Addition Subtraction (left to right)

56. 1.5 Algebra Review Rounding Off
For this class, unless instructed otherwise, round off to two decimal places, as soon as decimals occur.
You should have no more than two numbers to the right of the decimal point.

57. 1.5 Algebra Review Rounding Down
If there are three or more digits to the right of the decimal, look at the third digit. If it is less than 5, “round down” (drop the digits after the two digits after the decimal).
rounded = 5.84

58. 1.5 Algebra Review Rounding Up
If the third digit after the decimal is 5 or more, “round up”. Add 1 to the second digit after the decimal, carry if needed, and drop the digits after the two digits after the decimal.
rounded = 5.85

59. 1.1 Algebra Review