Question

The types of raw materials used to construct stone tools found at an archaeological site are shown below. A random sample of 1486 stone tools were obtained from a current excavation site.

Raw Material	Regional Percent of Stone Tools	Observed Number of Tools as Current excavation Site
Basalt	61.3%	894
Obsidian	10.6%	165
Welded Tuff	11.4%	183
Pedernal chert	13.1%	199
Other	3.6%	45

Use a 1% level of significance to test the claim that the regional distribution of raw materials fits the distribution at the current excavation site.

(a) What is the level of significance?


State the null and alternate hypotheses.

H₀: The distributions are the same.
H₁: The distributions are the same. H₀: The distributions are different.
H₁: The distributions are different.     H₀: The distributions are different.
H₁: The distributions are the same. H₀: The distributions are the same.
H₁: The distributions are different.

(b) Find the value of the chi-square statistic for the sample. (Round the expected frequencies to at least three decimal places. Round the test statistic to three decimal places.)


Are all the expected frequencies greater than 5?

Yes No    

What sampling distribution will you use?

binomial Student's t     chi-square normal uniform

What are the degrees of freedom?


(c) Find or estimate the P-value of the sample test statistic.

P-value > 0.100 0.050 < P-value < 0.100     0.025 < P-value < 0.050 0.010 < P-value < 0.025 0.005 < P-value < 0.010 P-value < 0.005

(d) Based on your answers in parts (a) to (c), will you reject or fail to reject the null hypothesis of independence?

Since the P-value > α, we fail to reject the null hypothesis. Since the P-value > α, we reject the null hypothesis.     Since the P-value ≤ α, we reject the null hypothesis. Since the P-value ≤ α, we fail to reject the null hypothesis.

(e) Interpret your conclusion in the context of the application.

At the 0.01 level of significance, the evidence is sufficient to conclude that the regional distribution of raw materials does not fit the distribution at the current excavation site. At the 0.01 level of significance, the evidence is insufficient to conclude that the regional distribution of raw materials does not fit the distribution at the current excavation site.    

Answer 1

The following table is obtained:

Categories	Observed	Expected	(fo-fe)2/fe
Category 1	894	1486*0.613=910.918	(894-910.918)2/910.918 = 0.314
Category 2	165	1486*0.106=157.516	(165-157.516)2/157.516 = 0.356
Category 3	183	1486*0.114=169.404	(183-169.404)2/169.404 = 1.091
Category 4	199	1486*0.131=194.666	(199-194.666)2/194.666 = 0.096
Category 5	45	1486*0.036=53.496	(45-53.496)2/53.496 = 1.349
Sum =	1486	1486	3.207