In: Statistics and Probability
The city of Tucson, Arizona, employs people to assess the value of homes for the purpose of establishing real estate tax. The city manager sends each assessor to the same five homes and ten compares the results. The information is given below, in thousands of dollars. Can we conclude that there is a difference in the assessors, at a significance level of 0.05?
Home | Smith | Norman | Thomas | Holiday |
A | 53 | 55 | 49 | 45 |
B | 50 | 51 | 52 | 53 |
C | 48 | 52 | 47 | 53 |
D | 70 | 68 | 65 | 64 |
E | 84 | 89 | 92 | 86 |
Part A:
Assessor A.
What is the null hypothesis statement for this problem?
B. What is the alternative hypothesis statement for this problem?
C. What is alpha for this analysis?
D. What is the most appropriate test for this problem? (choose one of the following)
a. F-Test Two-Sample for Variance
b. Anova: Single Factor
c. Anova: Two-Factor with Replication
d. Anova: Two-Factor without Replication
E. What is the value of the test statistic for the most appropriate analysis?
F. What is the value of the critical value for the most appropriate analysis?
G. Is it reasonable to conclude that there is a difference in the mean home value based on the assessor? (choose one of the following)
a. Yes
b. No
h. What is the p-value for this analysis?
Part B:
Home
A. What is the null hypothesis statement for this problem?
B. What is the alternative hypothesis statement for this problem?
C. What is alpha for this analysis?
D. What is the most appropriate test for this problem? (choose one of the following)
a. F-Test Two-Sample for Variance
b. Anova: Single Factor
c. Anova: Two-Factor with Replication
d. Anova: Two-Factor without Replication
E. What is the value of the test statistic for the most appropriate analysis?
F. What is the value of the critical value for the most appropriate analysis?
G. Is it reasonable to conclude that there is a difference in the value based on the home? (choose one of the following)
a. Yes
b. No
h. What is the p-value for this analysis?
you must show your work and you must use the appropriate formulas in Excel to answer the questions. SHOW ALL FORMULAS USED IN DETAILS.
Anova: Two-Factor Without Replication |
Anova: Two-Factor Without Replication | row data, j | Factor A | ||||||||||
Smith | Norman | Thomas | Holiday | total | count, n j | mean , x̅ j | std. dev., sj | sample variances, sj^2 | ( x̅ j - x̅̅)² | nj( x̅j - x̅̅)² | ||
A | 53 | 55 | 49 | 45 | 202 | A | 4 | 50.5 | 4.4347 | 19.667 | 116.640 | 466.560 |
B | 50 | 51 | 52 | 53 | 206 | B | 4 | 51.5 | 1.2910 | 1.667 | 96.040 | 384.160 |
C | 48 | 52 | 47 | 53 | 200 | C | 4 | 50 | 2.9439 | 8.667 | 127.690 | 510.760 |
D | 70 | 68 | 65 | 64 | 267 | D | 4 | 66.75 | 2.7538 | 7.583 | 29.703 | 118.810 |
E | 84 | 89 | 92 | 86 | 351 | E | 4 | 87.75 | 3.5000 | 12.250 | 699.603 | 2798.410 |
6 | 6 | |||||||||||
7 | 7 | |||||||||||
total | 305 | 315 | 305 | 301 | 1226 | SSA = total= | 4278.700 | |||||
SSA=Σnj( x̅j - x̅̅)² = | 4278.700 | |||||||||||
column data , i (Factor B) | Smith | Norman | Thomas | Holiday | SST = | Σ(Xij - X̅̅ ) = | 4428.2 | |||||
count, ni = | 5 | 5 | 5 | 5 | ||||||||
mean , x̅ i = | 61.000 | 63.000 | 61.000 | 60.200 | SSE = | SST-SSA-SSB = | 128.100 | |||||
std. dev., si = | 15.524 | 16.047 | 18.695 | 15.928 | ||||||||
sample variances, si^2 = | 241.000 | 257.500 | 349.500 | 253.700 | ||||||||
grand mean , x̅̅ = | ΣXij/Σn = | 61.3 | ||||||||||
square of deviation of sample mean from grand mean,( x̅ - x̅̅)² | 0.09 | 2.89 | 0.09 | 1.21 | ||||||||
TOTAL | ||||||||||||
SS(between)= SSB = Σni( x̅ i - x̅̅)² = | 0.45 | 14.45 | 0.45 | 6.05 | 21.4 |
so, SSA= 4278.700
SSB= 21.4
SSE= 128.100
df factor A(row) = r-1 = 4
df factor B(column) = c-1 = 3
here, N = 20
df error = (r-1)(c-1) = 12
mean square factor A , MSA = SSA/df= 1069.675
mean square(factor B) =MSB= SSB/df = 7.133333333
mean square error = MSE =SSE/df = 10.675
F-statistics
Factor A = MSA/MSE = 100.2037471
factor B = MSB/MSE= 0.668227947
ANOVA | |||||||
Source of Variation | SS | df | MS | F-stat | p-value | F-critical | Result |
Rows | 4278.7000 | 4 | 1069.6750 | 100.204 | 0.0000 | 3.2591667 | significant |
Columns | 21.4000 | 3 | 7.1333 | 0.668 | 0.5876 | 3.4902948 | not significant |
Error | 128.1000 | 12 | 10.6750 | ||||
Total | 4428.2000 | 19 | |||||
α = | 0.05 |
using above result, we can answer following question:
Part A:
Assessor A.
What is the null hypothesis statement for this problem?
there is no difference in the mean home value based on the assessor
B. What is the alternative hypothesis statement for this problem?
there is a difference in the mean home value based on the assessor
C. What is alpha for this analysis?
0.05
D. What is the most appropriate test for this problem? (choose one of the following)
d. Anova: Two-Factor without Replication
E. What is the value of the test statistic for the most appropriate analysis?
F-stat=0.6682
F. What is the value of the critical value for the most appropriate analysis?
F-critical=3.4903
G. Is it reasonable to conclude that there is a difference in the mean home value based on the assessor? (choose one of the following)
since F-stat<F-critical, do not reject Ho,
so, answer is
b. No
h. What is the p-value for this analysis?
0.5876
Part B:
Home
A. What is the null hypothesis statement for this problem?
there is no difference in the value based on the home
B. What is the alternative hypothesis statement for this problem?
there is a difference in the value based on the home
C. What is alpha for this analysis?
0.05
D. What is the most appropriate test for this problem? (choose one of the following)
d. Anova: Two-Factor without Replication
E. What is the value of the test statistic for the most appropriate analysis?
F-stat=100.2037471
F. What is the value of the critical value for the most appropriate analysis?
F-critical=3.2592
G. Is it reasonable to conclude that there is a difference in the value based on the home? (choose one of the following)
since, F-stat>f-critical, so, reject Ho
hence answer is
a. Yes
h. What is the p-value for this analysis?
p-value=0.000
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please revert for doubts