PSYC206 Lecture 8: Correlation
Pearson’s Correlation Coefficient
!Direction
!The sign (+/-) of r indicates the direction of the relationship
!Strength
!The absolute value of r indicates the strength of the relationship
!As a general rule, correlations between
!0 and ±.29 are weak relationship
!±.30 and ±.49 are moderate relationship
!±.50 and ±1.00 are strong relationship
!Significance
!We can test whether the correlation is significantly different from
zero (p < .05) infuences by the number of people in a sample
How much variance does exam anxiety account for in exam performance?
R2 = .194, so we are accounting for 19.4% of the variance in exam performance
with
exam anxiety
Are we accounting for a significant amount of variance with our regression
model?
Yes, F(1, 101) = 24.38, p < .001
Write out the regression equation for this example.
Exam Performance = 106.071 + (-.666 x Exam Anxiety)
What does the intercept (b0) tell you?
We predict a score of 106.071 on the exam when exam anxiety is 0
What does the slope (b1) tell you?
For a 1 unit increase in exam anxiety, exam performance decreases by .666
points
If someone had an exam anxiety score of 80, what would we predict for their
exam performance?
Exam Performance = 106.071 + (-.666 x 80) = 106.071 + (-53.28) = 52.791
Exam Performance = 106.071 + (-.666 x 20) = 106.071 + (-13.32) = 92.751
Sleep has a direct cause on decreasing stress
-
Stress is effecting your sleep
-
Screaming children (environment) is producing high levels of stress and low levels of
sleep
-
r means correlation
-
No relationship
Persons correlation is
the correlation
coefficient. Stars
indicted its significant
R is correlation so
for r squared look at
Pearsons and
square the number
to get the effect size
Scores on each variable from each person
Contiumm of scores
Looking to see if there is a
linear relationship, drawing
a straight line through the
plots
Look at scatter plots go
along one variable to other
is about the same
Blue line is
regression
M stands for model
Total sum of squares
Week 8
Saturday, 28 April 2018
9:59 PM
Pearson’s Correlation Coefficient
!Direction
!The sign (+/-) of r indicates the direction of the relationship
!Strength
!The absolute value of r indicates the strength of the relationship
!As a general rule, correlations between
!0 and ±.29 are weak relationship
!±.30 and ±.49 are moderate relationship
!±.50 and ±1.00 are strong relationship
!Significance
!We can test whether the correlation is significantly different from
zero (p < .05) infuences by the number of people in a sample
How much variance does exam anxiety account for in exam performance?
R2 = .194, so we are accounting for 19.4% of the variance in exam performance
with
exam anxiety
Are we accounting for a significant amount of variance with our regression
model?
Yes, F(1, 101) = 24.38, p < .001
Write out the regression equation for this example.
Exam Performance = 106.071 + (-.666 x Exam Anxiety)
What does the intercept (b0) tell you?
We predict a score of 106.071 on the exam when exam anxiety is 0
What does the slope (b1) tell you?
For a 1 unit increase in exam anxiety, exam performance decreases by .666
points
If someone had an exam anxiety score of 80, what would we predict for their
exam performance?
Exam Performance = 106.071 + (-.666 x 80) = 106.071 + (-53.28) = 52.791
Exam Performance = 106.071 + (-.666 x 20) = 106.071 + (-13.32) = 92.751
Sleep has a direct cause on decreasing stress
-
Stress is effecting your sleep
-
Screaming children (environment) is producing high levels of stress and low levels of
sleep
-
r means correlation
-
No relationship
Persons correlation is
the correlation
coefficient. Stars
indicted its significant
R is correlation so
for r squared look at
Pearsons and
square the number
to get the effect size
Scores on each variable from each person
Contiumm of scores
Looking to see if there is a
linear relationship, drawing
a straight line through the
plots
Look at scatter plots go
along one variable to other
is about the same
Blue line is
regression
M stands for model
Total sum of squares
Week 8
Saturday, 28 April 2018
9:59 PM
Pearson’s Correlation Coefficient
!Direction
!The sign (+/-) of r indicates the direction of the relationship
!Strength
!The absolute value of r indicates the strength of the relationship
!As a general rule, correlations between
!0 and ±.29 are weak relationship
!±.30 and ±.49 are moderate relationship
!±.50 and ±1.00 are strong relationship
!Significance
!We can test whether the correlation is significantly different from
zero (p < .05) infuences by the number of people in a sample
How much variance does exam anxiety account for in exam performance?
R2 = .194, so we are accounting for 19.4% of the variance in exam performance
with
exam anxiety
Are we accounting for a significant amount of variance with our regression
model?
Yes, F(1, 101) = 24.38, p < .001
Write out the regression equation for this example.
Exam Performance = 106.071 + (-.666 x Exam Anxiety)
What does the intercept (b0) tell you?
We predict a score of 106.071 on the exam when exam anxiety is 0
What does the slope (b1) tell you?
For a 1 unit increase in exam anxiety, exam performance decreases by .666
points
If someone had an exam anxiety score of 80, what would we predict for their
exam performance?
Exam Performance = 106.071 + (-.666 x 80) = 106.071 + (-53.28) = 52.791
Exam Performance = 106.071 + (-.666 x 20) = 106.071 + (-13.32) = 92.751
Sleep has a direct cause on decreasing stress
-
Stress is effecting your sleep
-
Screaming children (environment) is producing high levels of stress and low levels of
sleep
-
r means correlation
-
No relationship
Persons correlation is
the correlation
coefficient. Stars
indicted its significant
R is correlation so
for r squared look at
Pearsons and
square the number
to get the effect size
Scores on each variable from each person
Contiumm of scores
Looking to see if there is a
linear relationship, drawing
a straight line through the
plots
Look at scatter plots go
along one variable to other
is about the same
Blue line is
regression
M stands for model
Total sum of squares
Week 8
Saturday, 28 April 2018 9:59 PM
Document Summary
Sleep has a direct cause on decreasing stress. Screaming children (environment) is producing high levels of stress and low levels of sleep r means correlation. The sign (+/-) of r indicates the direction of the relationship. The absolute value of r indicates the strength of the relationship. We can test whether the correlation is significantly different from zero (p < . 05) infuences by the number of people in a sample of. R is correlation so for r squared look at. Pearsons and square the number to get the effect size. Looking to s linear relati a straight lin plots. Look at scatter plots go along one variable to other is about the same at ize each person of scores to see if there is a elationship, drawing ht line through the. Total sum o tands for model um of squares. R2 = . 194, so we are accounting for 19. 4% of the variance in exam performance with exam anxiety.
