1. Personality Research Methods: Correlation and Reliability

2. Measuring personality variables
What is a variable?
What kinds of variables are there?
Categorical variables (examples: gender, political affiliation)
Continuous variables (height, weight)
How can we measure an aspect of personality as a variable?
Psychometrics (psyche – mind, metric – measure): an applied branch of psychology that deals with psycho-logical measurement
The most commonly used approach to study human personality: the self-report questionnaire measure

3. I am socially somewhat awkward.
Personality Inventory Please read the following items and decide how well they describe your personality. Respond to each according to the following list of alternatives:
a. very much unlike me
b. somewhat unlike me
c. somewhat like me
d. very much like me
I am socially somewhat awkward.
I don’t find it hard to talk with strangers
I feel tense when I’m with people I don’t know well.
When conversing I worry about saying something dumb.
I feel nervous when speaking to someone in authority.
I am often uncomfortable at parties and other social functions.
I feel inhibited in social situations.
I have trouble looking someone right in the eye.
I am more shy with members of the opposite sex.

4. Correlating variables
What is a variable?
What kinds of variables are there?
Categorical variables (examples: gender, political affiliation)
Continuous variables (height, weight)
Correlating two variables
Measure the two variables (X and Y) as accurately as you can
Plot the variables as X-Y coordinates on a two-dimensional space
Examine the shape of the “scatterplot” to estimate the size and “direction” of the correlation
Compute the correlation coefficient using the correct mathematical formula (or let the computer do it for you)

5. Standard scores in a normal distribution

6. NAME
HEIGHT (X)
WEIGHT (Y)
Allport, Allen 69
175
Bimiup, Scotty 68
159
Brewer, Joseph 71
177
Derrickson, Derek
150
Dorman, Carlton 67
162
Horne, Karyn 65
134
Ingram, Irene 64
121
James, Jocelyn
125
Jones, Ernie
158
Lang, Fred
161
Kelly, Christine 63
119
Lime, Nora
128
etc.

15. Reliability in personality measurement
Reliability (consistency of measurement, or agreement)
Internal consistency
Item-to-total correlation
Split-half reliability
Cronbach’s alpha
Parallel forms reliability
Inter-observer reliability
Test-retest reliability

16. I am socially somewhat awkward.
Personality Inventory Please read the following items and decide how well they describe your personality. Respond to each according to the following list of alternatives:
a. very much unlike me
b. somewhat unlike me
c. somewhat like me
d. very much like me
I am socially somewhat awkward.
I don’t find it hard to talk with strangers
I feel tense when I’m with people I don’t know well.
When conversing I worry about saying something dumb.
I feel nervous when speaking to someone in authority.
I am often uncomfortable at parties and other social functions.
I feel inhibited in social situations.
I have trouble looking someone right in the eye.
I am more shy with members of the opposite sex.

17. Reliability in personality measurement
Reliability (consistency of measurement, or agreement)
Internal consistency
Item-to-total correlation
Split-half reliability
Cronbach’s alpha
Parallel forms reliability
Inter-observer reliability
Test-retest reliability

18. Item-to-total correlations
SHY1
SHY2
SHY3
SHY4
SHY5
SHY6
SHY7
SHY8
SHY9
SHY
.68
.64
.67
.65
.73
.75
.57
.61

19. Reliability in personality measurement
Reliability (consistency of measurement, or agreement)
Internal consistency
Item-to-total correlation
Split-half reliability
Cronbach’s alpha
Parallel forms reliability
Inter-observer reliability
Test-retest reliability

21. Reliability in personality measurement
Reliability (consistency of measurement, or agreement)
Internal consistency
Item-to-total correlation
Split-half reliability
Cronbach’s alpha
Parallel forms reliability
Inter-observer reliability
Test-retest reliability

22. Reliability (internal consistency) Cronbach’s alpha =
Reliability (internal consistency) Cronbach’s alpha = Factor pattern Factor 1
SHY1
.69
SHY2
.62
SHY3
.67
SHY4
.66
SHY5
.65
SHY6
.75
SHY7
.78
SHY8
.54
SHY9
.58

23. Reliability in personality measurement
Reliability (consistency of measurement, or agreement)
Internal consistency
Item-to-total correlation
Split-half reliability
Cronbach’s alpha
Parallel forms reliability
Inter-observer reliability
Test-retest reliability