Question

A regression was run to determine if there is a relationship between the happiness index (y) and life expectancy in years of a given country (x).The results of the regression were:
y = a + bx
a = -0.762
b = 0.119
r2 = 0.8649
r = 0.93
A) Write the equation of the Least Squares Regression line of the form y = + x
B) If a country increases its life expectancy, the happiness index will increase or decrease?
C) If the life expectancy is increased by 3.5 years in a certain country, how much will the happiness index change?
D) Use the regression line to predict the happiness index of a country with a life expectancy of 67 years.

Answer 1

Answer:

(A) $y=-0.762+0.119x$

(B) If a country increases its life expectancy, the happiness index will increase.

(C) If the life expectancy is increased by 3.5 years in a certain country, the happiness index will increase by 0.4165.

(D) If the life expectancy is 67 years in a certain country, the happiness index will be 7.21.

Step-by-step explanation:

A regression analysis was performed to determine if there is a relationship between the happiness index (y) and life expectancy in years of a given country (x).

The output of the regression analysis are as follows:

a = -0.762

b = 0.119

r² = 0.8649

r = 0.93

(A)

The equation of the Least Squares Regression line of the form y = _ + _ x is:

$y=-0.762+0.119x$

(B)

The correction between the variables happiness index (y) and life expectancy in years of a given country (x) is, 0.93.

The correlation coefficient is positive. This implies that there is a positive relation between the two variables, i.e. as the value of life expectancy in years increases the happiness index also increases.

Thus, if a country increases its life expectancy, the happiness index will increase.

(C)

Compute the value of y for x = x + 3.5 as follows:

$y=-0.762+0.119x$

  $=-0.762+0.119\times (x+3.5)\\\\=(-0.762+0.119x)+0.4165\\\\=y+0.4165$

Thus, if the life expectancy is increased by 3.5 years in a certain country, the happiness index will increase by 0.4165.

(D)

Compute the value of y for x = 67 as follows:

$y=-0.762+0.119x$

  $=-0.762+0.119\times 67\\\\=-0.762+7.973\\\\=7.211\\\\\approx 7.21$

Thus, if the life expectancy is 67 years in a certain country, the happiness index will be 7.21.