How to find the correlation coefficient.
Bicycle helmet use. Table lists data from a cross-sectional survey of bicycle safety. The explanatory variable is a measure of neighbourhood socioeconomic status (variable_RFM). The response variable is percent of bicycle riders wearing a helmet (P_Helm).
Percent of school children getting free or reduced-fee lunches at school (variable P_RFM) and percent of bicycle riders wearing a helmet (variable P_HELM). Data for this research was recorded by field observers in October of 1994.
|
I (i)
|
School
|
P_RFM
|
P-HELM
|
|
|
|
|
|
|
1
|
Fair Oaks
|
50
|
22.1
|
|
2
|
Strandwood
|
11
|
35.9
|
|
3
|
Walnut Acres
|
2
|
57.9
|
|
4
|
Disc Bay
|
19
|
22.2
|
|
5
|
Belshaw
|
26
|
42.4
|
|
6
|
Kennedy
|
73
|
5.8
|
|
7
|
Cassell
|
81
|
3.6
|
|
8
|
Miner
|
51
|
21.4
|
|
9
|
Sedgewick
|
11
|
55.2
|
|
10
|
Sakamoto
|
2
|
33.3
|
|
11
|
Toyon
|
19
|
32.4
|
|
12
|
Lietz
|
25
|
38.4
|
|
13
|
Los Arboles
|
84
|
46.6
|
Compute r for all 13 data points. Define the correlation strength.