In: Statistics and Probability
5. You are given the following table.
X | Y |
1,000 | 500 |
3,000 | 400 |
7,000 | 750 |
12,000 | 1,000 |
15,500 | 1,200 |
17,000 | 1,000 |
17,500 | 1,800 |
21,000 | 2000 |
22,800 | 2,200 |
23,000 | 3,000 |
a. Decide which variable should be the independent variable and which should be the dependent variable.
b. Draw a scatter plot of the data.
c. Does it appear from inspection that there is a relationship between the variables? Why or why not?
d. Calculate the least-squares line. Put the equation in the form of: ŷ = a + bx.
e. Find the correlation coefficient. Is it significant?
f. Find estimated total values for column Y for 16,000, 24,000, and 36,000 16,000= 24,000= 36,000=
g. Does it appear that a line is the best way to fit the data? Why or why not? h. Are there any outliers in the data?
i. Based on these results, what would be the probate fees and taxes for an estate that does not have any assets?
j. What is the slope of the least-squares (best-fit) line? Interpret the slope.
5)
X: independent
Y : dependent
................
b)
c)
there appear to be linear , positive relation between x and y
...........
d)
ΣX | ΣY | Σ(x-x̅)² | Σ(y-ȳ)² | Σ(x-x̅)(y-ȳ) | |
total sum | 139800 | 13850 | 573936000 | 6310250.0 | 53587000.00 |
mean | 13980.00 | 1385.00 | SSxx | SSyy | SSxy |
sample size , n = 10
here, x̅ = Σx / n= 13980.00 ,
ȳ = Σy/n =
1385.00
SSxx = Σ(x-x̅)² =
573936000.0000
SSxy= Σ(x-x̅)(y-ȳ) =
53587000.0
estimated slope , ß1 = SSxy/SSxx =
53587000.0 / 573936000.000
= 0.0934
intercept, ß0 = y̅-ß1* x̄ =
79.7216
so, regression line is Ŷ =
79.7216 + 0.0934
*x
..........................
e)
correlation coefficient , r = Sxy/√(Sx.Sy)
= 0.8904
correlation hypothesis test
Ho: ρ = 0
Ha: ρ ╪ 0
n= 10
alpha,α = 0.05
correlation , r= 0.8904
t-test statistic = r*√(n-2)/√(1-r²) =
5.534
DF=n-2 = 8
p-value = 0.0006
Decison: p value < α , So, Reject
Ho
................
f)
Predicted Y at X= 16000 is
Ŷ = 79.72161 +
0.093368 * 16000 =
1573.602
Predicted Y at X= 24000 is
Ŷ = 79.72161 +
0.093368 * 24000 =
2320.543
Predicted Y at X= 32000 is
Ŷ = 79.72161 +
0.093368 * 32000 =
3067.483
..............
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