In: Statistics and Probability
There is an archaeological study area located in southwestern New Mexico. Potsherds are broken pieces of prehistoric Native American clay vessels. One type of painted ceramic vessel is called Mimbres classic black-on-white. At three different sites, the number of such sherds was counted in local dwelling excavations.
Site I | Site II | Site III |
64 | 26 | 15 |
35 | 17 | 32 |
22 | 54 | 65 |
11 | 68 | 28 |
77 | 16 | |
54 | 13 | |
20 |
Shall we reject or not reject the claim that there is no difference in population mean Mimbres classic black-on-white sherd counts for the three sites? Use a 1% level of significance.
(a) What is the level of significance?
State the null and alternate hypotheses.
H0: μ1 = μ2 = μ3; H1: Exactly two means are equal.H0: μ1 = μ2 = μ3; H1: Not all the means are equal. H0:μ1 = μ2 = μ3; H1: At least two means are equal.H0: μ1 = μ2 = μ3; H1: All three means are different.
(b) Find SSTOT,
SSBET, and
SSW and check that
SSTOT =
SSBET +
SSW. (Round your answers to three
decimal places.)
SSTOT | = | |
SSBET | = | |
SSW | = |
Find d.f.BET,
d.f.W,
MSBET, and
MSW. (Round your answers for
MSBET, and MSW to
two decimal places.)
d.f.BET | = | |
d.f.W | = | |
MSBET | = | |
MSW | = |
Find the value of the sample F statistic. (Round your
answer to two decimal places.)
What are the degrees of freedom?
d.f.N | = |
d.f.D | = |
(c) Find the P-value of the sample test statistic.
P-value > 0.1000.050 < P-value < 0.100 0.025 < P-value < 0.0500.010 < P-value < 0.0250.001 < P-value < 0.010P-value < 0.001
(d) Based on your answers in parts (a) to (c), will you reject or
fail to reject the null hypothesis?
Since the P-value is greater than the level of significance at α = 0.01, we do not reject H0.Since the P-value is less than or equal to the level of significance at α = 0.01, we reject H0. Since the P-value is greater than the level of significance at α = 0.01, we reject H0.Since the P-value is less than or equal to the level of significance at α = 0.01, we do not reject H0.
(e) Interpret your conclusion in the context of the
application.
At the 1% level of significance there is insufficient evidence to conclude that the means are not all equal.At the 1% level of significance there is sufficient evidence to conclude that the means are all equal. At the 1% level of significance there is insufficient evidence to conclude that the means are all equal.At the 1% level of significance there is sufficient evidence to conclude that the means are not all equal.
(f) Make a summary table for your ANOVA test. (Round your answers
for SS to three decimal places, your MS and F Ratio to two
decimal places, and your P-value to four decimal
places.)
Source of Variation |
Sum of Squares |
Degrees of Freedom |
MS | F Ratio |
P-Value | Test Decision |
Between groups | ---Select--- p-value > 0.100 0.050 < p-value < 0.100 0.025 < p-value < 0.050 0.010 < p-value < 0.025 0.001 < p-value < 0.010 p-value < 0.001 | ---Select--- Reject H0. Do not reject H0. | ||||
Within groups |
Solution:-)
A) The level of significance is 0.01.
B) The null and alternative hypotheses are
\
That is all the means are equal .
At least none of them are equal.
C) From above the output of R, we have
SSTOT | 6637 | |
SSBET | 452 | |
SSW | 6185 |
We have the following results,
d.f.BET = 2 , d.f.W = 11 , MSBET = 226.2 , MSW= 562.3
D) The value of the sample F statistic is
e) The P-value of the sample test statistic is 0.678 > 0.01
f) As the p-value is greater than significance level, therefore we fail to reject the null hypothesis at significance level
g) .At the 1% level of significance there is sufficient evidence to conclude that the means are all equal. Therefore null hypothesis is accepted. All the means are equal.
h) The summary table will be
Source of Variation |
Sum of Squares |
Degrees of Freedom |
MS | P-Value | Test Decision |
|
Between groups | 452 | 2 | 226.2 | 0.678 | Therefore,Do not reject H0. | |
Within groups | 6185 | 11 | 562.3 | As p-value> 0.01 |