Question

Can use of an online plagiarism-detection system reduce plagiarism in student research papers? The paper "Plagiarism and Technology: A Tool for Coping with Plagiarism" describes a study in which randomly selected research papers submitted by students during five semesters were analyzed for plagiarism.† For each paper, the percentage of plagiarized words in the paper was determined by an online analysis. In each of the five semesters, students were told during the first two class meetings that they would have to submit an electronic version of their research papers and that the papers would be reviewed for plagiarism. Suppose that the number of papers sampled in each of the five semesters and the means and standard deviations for percentage of plagiarized words are as given in the accompanying table.

Semester	n	Mean	Standard deviation
1	39	6.34	3.75
2	43	3.32	3.09
3	32	1.77	3.25
4	32	1.81	3.12
5	34	1.50	2.39

For purposes of this exercise, assume that the conditions necessary for the ANOVA F test are reasonable. Do these data provide evidence to support the claim that mean percentage of plagiarized words is not the same for all five semesters? Test the appropriate hypotheses using

α = 0.05.

Calculate the test statistic. (Round your answer to two decimal places.)

F =  

Answer 1

from given data:

Group	ni	x̅i	S2i	ni*(Xi-Xgrand)2	(ni-1)*S2i
1	39	6.34	14.063	412.811	534.38
2	43	3.32	9.548	2.343	401.02
3	32	1.77	10.563	55.466	327.44
4	32	1.81	9.734	52.147	301.77
5	34	1.5	5.712	85.583	188.50
	grand mean=	3.0866		608.351	1753.10
				SSTr	SSE

Source	SS	df	MS	F	Fcrit
between	608.3511	4	152.0878	15.18	2.423
within	1753.10	175	10.0177
total	2361.45	179

from above test statistic F =15.18

as test statitic is higher than critical value we reject null hypothesis

and conclude that mean percentage of plagiarized words is not the same for all five semesters .