Given the sales list S, and the temperature list T.
S:[34, 39, 40, 36, 46, 47, 54, 27, 31, 56]
T:[71.0, 73.8, 74.9, 71.4, 75.0, 76.9, 79.4, 68.6, 70.0, 81.4]
n=10 = number of observations in each list.
We need the correlation coefficient ρ to select the right choice of answers.
We first calculate the mean μ and standard deviation σ of each list
We are now ready to calculate the correlation coefficient ρ :
=
0.9848Because the correlation coefficient, ρ , is close to one, the ice cream sales increase markedly with a rise in temperature.
Note:
a correlation close to 1 means both increase (or decrease)
a correlation close to -1 means one increases while the other decreases
correlation close to 0 means one does not quite affect the other.