Question

Can people tell the difference between a female nose and a male nose? Eight Caucasian males...

Can people tell the difference between a female nose and a male nose? Eight Caucasian males and eight Caucasian females posed for nose photos. The article states that none of the volunteers wore nose studs or had prominent nasal hair. Each person placed a black Lycra tube over his or her head in such a way that only the nose protruded through a hole in the material. Photos were then taken from three different angles: front view, three-quarter view, and profile. These photos were shown to a sample of undergraduate students. Each student in the sample was shown one of the nose photos and asked whether it was a photo of a male or a female; and the response was classified as either correct or incorrect. The accompanying table was constructed using summary values reported in the article. Is there evidence that the proportion of correct sex identifications differs for the three different nose views? Test the appropriate hypotheses using a .05 significance level. (Round your answer to two decimal places.)

Sex ID View
Front Profile Three-Quarter
Correct 29 26 28
Incorrect 11 14 12


χ2 =  

P-value interval

p < 0.001

0.001 ≤ p < 0.01    

0.01 ≤ p < 0.05

0.05 ≤ p < 0.10

p ≥ 0.10

Homework Answers

Answer #1
Applying chi square test of independence:
Expected Ei=row total*column total/grand total Front Profile three quarter Total
Correct 27.6667 27.6667 27.6667 83
Incorrect 12.3333 12.3333 12.3333 37
total 40 40 40 120
chi square    χ2 =(Oi-Ei)2/Ei Front Profile three quarter Total
Correct 0.064 0.100 0.004 0.1687
Incorrect 0.144 0.225 0.009 0.3784
total 0.2084 0.3256 0.0130 0.5471
test statistic X2 = 0.55

p ≥ 0.10

Fail to reject the null hypothesis

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