Power point 4
Linear correlation coefficient
scatter diagram
Correlation coefficients
pearson
(Quantitative variable)
spearman (Qualitative variable)
Example: the following data represent the weight and
height of 20 patients.
weight
Height
weight
Height
1
80
160
11
80
159
2
72
140
12
90
180
3
94
188
13
68
137
4
78
156
14
77
156
5
80
161
15
73
147
6
92
180
16
77
155
7
78
157
17
70
140
8
77
155
18
90
182
9
86
174
19
92
185
10
71
143
20
69
139
Find the correlation coefficient between weight and height .
Example(age): Find the correlation coefficient between age and
sex.
Which is the independent variable?
Which is the dependent variable?
Height is independent
Weight is dependent
simple linear regression model
dependent
independent
Example: the following data represent the weight and
height of 20 patients.
weight
Height
weight
Height
1
80
160
11
80
159
2
72
140
12
90
180
3
94
188
13
68
137
4
78
156
14
77
156
5
80
161
15
73
147
6
92
180
16
77
155
7
78
157
17
70
140
8
77
155
18
90
182
9
86
174
19
92
185
10
71
143
20
69
139
Then regression equation:
Weight = - 0.061 + 0.499 height
find the value of the weight when the height is 145?