In: Statistics and Probability
Colas per week Bone Mineral Density (grams per cubic centimeter)
0 0.907
0 0.896
1 0.881
1 0.870
2 0.853
2 0.835
2 0.836
3 0.816
4 0.789
5 0.767
5 0.762
6 0.733
7 0.704
7 0.714
7 0.710
The least-squares regression line treating cola consumption per week as the explanatory variable...
A) Y with caret = ___x + (___)
B) Interpert the slope ___
C) Interpret the y-intercept?
D) Predict the bone mineral density of the femoral neck of a woman who consumes two colas per week.
E) The researchers found a woman who consumed two colas per week to have a bone mineral density of ___g/cm3. this woman's bone density above or below average among all women who consume two colas per week?
The data provided is shown below:
Colas per week | Bone Mineral Density (grams per cubic centimeter) |
0 | 0.907 |
0 | 0.896 |
1 | 0.881 |
1 | 0.87 |
2 | 0.853 |
2 | 0.835 |
2 | 0.836 |
3 | 0.816 |
4 | 0.789 |
5 | 0.767 |
5 | 0.762 |
6 | 0.733 |
7 | 0.704 |
7 | 0.714 |
7 | 0.71 |
The independent variable is X, and the dependent variable is Y. In order to compute the regression coefficients, the following table needs to be used:
X | Y | X*Y | X2 | Y2 | |
0 | 0.907 | 0 | 0 | 0.822649 | |
0 | 0.896 | 0 | 0 | 0.802816 | |
1 | 0.881 | 0.881 | 1 | 0.776161 | |
1 | 0.87 | 0.87 | 1 | 0.7569 | |
2 | 0.853 | 1.706 | 4 | 0.727609 | |
2 | 0.835 | 1.67 | 4 | 0.697225 | |
2 | 0.836 | 1.672 | 4 | 0.698896 | |
3 | 0.816 | 2.448 | 9 | 0.665856 | |
4 | 0.789 | 3.156 | 16 | 0.622521 | |
5 | 0.767 | 3.835 | 25 | 0.588289 | |
5 | 0.762 | 3.81 | 25 | 0.580644 | |
6 | 0.733 | 4.398 | 36 | 0.537289 | |
7 | 0.704 | 4.928 | 49 | 0.495616 | |
7 | 0.714 | 4.998 | 49 | 0.509796 | |
7 | 0.71 | 4.97 | 49 | 0.5041 | |
Sum = | 52 | 12.073 | 39.342 | 272 | 9.786367 |
Based on the above table, the following is calculated:
Therefore, based on the above calculations, the regression coefficients (the slope m, and the y-intercept n) are obtained as follows:
Therefore, we find that the regression equation is:
Y = 0.8998 - 0.0274 X
B. The slope of -0.0274 is interpreted as follows. As the value of the X variable increases by 1, the value of the Y variable decreases by 0.0274. It is the value by which Y increases for ever unit increase in X.
C.
The y-intercept is the expected mean value of Y when X=0
D.
When X = 2
Y = 0.8998 - 0.0274 * 2 = 0.845
Hence the bone mineral density of the femoral neck of a woman who consumes two colas per week is 0.845 g/cm3
E.
0.845 g/cm3
This woman's bone density is above average among all women who consume two colas per week.
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