Question

In an effort to determine whether any correlation exists between the price of stocks of airlines, an analyst sampled six days of activity of the stock market spread out over 4 months. Using the following prices of Delta stock and Southwest stock, compute the coefficient of correlation. Stock prices have been rounded off to the nearest tenth for ease of computation. Delta Southwest 45.96 38.76 46.8 45.41 47.93 15.7 51.78 49.58 52.17 44.34 47.36 18.1 (Round the intermediate values to 2 decimal places. Round your answer to 3 decimal places.) r =

Delta	south
45.96	38.76
47.1	45.41
47.93	16.1
51.78	49.58
52.17	44.34
47.36	18.1

Answer 1

Solution

Back-up Theory

Correlation coefficient, r = Sxy/sqrt(Sxx. Syy), where

Mean X = Xbar = (1/n) Σ(i = 1 to n)x_i Mean Y = Ybar = (1/n) Σ(i = 1 to n)y_i Sxx = Σ(i = 1 to n)(x_i – Xbar)² Syy = Σ(i = 1 to n)(y_i – Ybar)² Sxy = Σ(i = 1 to n){(x_i – Xbar)(y_i – Ybar)}

Now to work out the solution,

Let x = Delta stock price and y = Southwest stock price. Then, by the above formula,

the coefficient of correlation between the prices of the two stocks, r = 0.460 Answer

Details of calculations

n	6
Xbar	48.72
ybar	35.38
Sxx	33.98
Syy	1064.26
Sxy	87.52
r	0.4602

DONE