In: Statistics and Probability
It is thought that basketball teams that make too many fouls in a game tend to lose the game even if they otherwise play well. Let x be the number of fouls more than (i.e., over and above) the opposing team. Let y be the percentage of times the team with the larger number of fouls wins the game.
x | 1 | 4 | 5 | 6 |
y | 51 | 42 | 33 | 26 |
A. given Σx = 16, Σy = 152, Σx2 = 78, Σy2 = 6130, Σxy = 540, and r ≈ −0.966
Verify the given sums Σx, Σy, Σx2, Σy2, Σxy, and the value of the sample correlation coefficient r. (Round your value for r to three decimal places.)
Σx = | |
Σy = | |
Σx2 = | |
Σy2 = | |
Σxy = | |
r = |
B. Find x, and y. Then find the equation of the least-squares line = a + bx. (Round your answers for x and y to two decimal places. Round your answers for a and b to three decimal places.)
x | = | |
y | = | |
= | + x |
C. Find the value of the coefficient of determination r2. What percentage of the variation in y can be explained by the corresponding variation in x and the least-squares line? What percentage is unexplained? (Round your answer for r2 to three decimal places. Round your answers for the percentages to one decimal place.)
r2 = | |
explained | % |
unexplained | % |
If a team had x = 3 fouls over and above the opposing
team, what does the least-squares equation forecast for y?
(Round your answer to two decimal places.)
%
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Σx = 16
Σy = 152
Σx2 = 78
Σy2 = 6130
Σxy = 540
r = −0.966
B. Find x, and y. Then find the equation of the least-squares line = a + bx. (Round your answers for x and y to two decimal places. Round your answers for a and b to three decimal places.)
x bar=16/4 | 4 | |
y bar=152/4 | 38 | |
y= | 57.429 | +(-4.857) x |
y=57.429+(-4.857)x
C. Find the value of the coefficient of determination r2. What percentage of the variation in y can be explained by the corresponding variation in x and the least-squares line? What percentage is unexplained? (Round your answer for r2 to three decimal places. Round your answers for the percentages to one decimal place.)
r2 | 0.933 |
explained | 93.3% |
unexplained | 6.7% |
If a team had x = 3 fouls over and above the opposing
team, what does the least-squares equation forecast for y?
(Round your answer to two decimal places.)
42.86%
Using Excel<data<data analysis<regression
Regression Analysis | ||||||
r² | 0.933 | |||||
r | -0.966 | |||||
Std. Error | 3.443 | |||||
n | 4 | |||||
k | 1 | |||||
Dep. Var. | y | |||||
ANOVA table | ||||||
Source | SS | df | MS | F | p-value | |
Regression | 330.2857 | 1 | 330.2857 | 27.86 | .0341 | |
Residual | 23.7143 | 2 | 11.8571 | |||
Total | 354.0000 | 3 | ||||
Regression output | confidence interval | |||||
variables | coefficients | std. error | t (df=2) | p-value | 95% lower | 95% upper |
Intercept | 57.429 | 4.06 | 14.13 | 0.00 | 39.94 | 74.91 |
x | -4.857 | 0.9203 | -5.278 | .0341 | -8.8168 | -0.8974 |
Predicted values for: y | ||||||
95% Confidence Interval | 95% Prediction Interval | |||||
x | Predicted | lower | upper | lower | upper | Leverage |
3 | 42.857 | 34.457 | 51.257 | 25.826 | 59.888 | 0.321 |