Emma Sibley
4,6,10,16,18,22 skip c&d, 24
4. This equation includes the slope (b), which indicates the rate and direction the Y scores change,
and the Y intercept (a), which is the value of Y when the line crosses the Y axis and the starting value
from the Y scores change.
6. When performing correlation and regression procedures, the X variable is called the predictor and
the Y variable is called the criterion.
10. Procedures for describing the relationship when multiple predictor (X variables are simultaneously
used to predict scores on one criterion (Y) variable.
16.
a. Poindexter finds the correlation between the number of hours studied and the number of errors
made on a statistics test as r=
−
0.80
As the correlation value is close to -1, it depicts a strong negative correlation between them.
The correlation between the speed of taking the test and the number of errors made on the test is
r=
−
0.40.
The correlation value depicts a moderate negative correlation between them.
As
−
0.40
×
2=
−
0.80
−
0.40
×
2=
−
0.80, it can be said that the correlation value between the number of
hours studied and the number of errors made on a statistics test is twice that of the correlation value
between the speed of taking the test and the number of errors made on the test. Therefore,
statement is correct.
b. The correlation between hours studied and the errors made is more (twice) compared to the other
correlation, so the number of hours studied is more strongly associated with the errors made,
compared to the speed of the test.
18. The correlation coe
ﬃ
cient for variables A and B is 0.20 and the correlation coe
ﬃ
cient for variables
C and B is -0.40. Therefore, a conclusion can be drawn that variables C and B are twice as strongly
correlated as variables A and B. Based on the value of r, variables A and B have a relatively weak,
positive correlation. The other pair, variables C and B, have a negative correlation, but the correlation
is twice as strong. Thus, the relationship between C and B is more useful scientifically.
22.
a.
b.
24.
a. Both study whether and how changes in one variable correlate with changes in another, require
careful measurement of at least one uncontrolled variable, should eliminate and/or take account of
extraneous variables that might a
ff
ect those being measured.
b manipulation