28. There is evidence indicating that people with visible tattoos are viewed mor

Question

28. There is evidence indicating that people with visible tattoos are viewed more negatively than people without visible tattoos. On a 7-point scale, people rated a woman without a tattoo with an average rating of = 4.9, the standard deviation of these scores was = 0.84. The researcher modified the picture of the woman so she now had a tattoo of Groot on her left arm. This was shown to a sample of n = 16 students and the students used the same 7-point scale to rate the attractiveness of the woman. The average score for the photo with the tattoo was M = 4.2. (8 points)

a. Do the data indicate a significant difference in rated attractiveness when the woman appeared to have a tattoo? Use a two-tailed test with = 0.05. (Show all steps.)
b. Compute Cohen’s d to measure the size of the effect IF it exists. c. Write a sentence describing the outcome of the hypothesis test and the measure of effect size as it would appear in a research report.

Explanation / Answer

a.
Given that,
population mean(u)=4.9
standard deviation, =0.84
sample mean, x =4.2
number (n)=16
null, Ho: =4.9
alternate, H1: !=4.9
level of significance, = 0.05
from standard normal table, two tailed z /2 =1.96
since our test is two-tailed
reject Ho, if zo < -1.96 OR if zo > 1.96
we use test statistic (z) = x-u/(s.d/sqrt(n))
zo = 4.2-4.9/(0.84/sqrt(16)
zo = -3.33
| zo | = 3.33
critical value
the value of |z | at los 5% is 1.96
we got |zo| =3.33 & | z | = 1.96
make decision
hence value of | zo | > | z | and here we reject Ho
p-value : two tailed ( double the one tail ) - ha : ( p != -3.33 ) = 0
hence value of p0.05 > 0, here we reject Ho
ANSWERS
---------------
null, Ho: =4.9
alternate, H1: !=4.9
test statistic: -3.33
critical value: -1.96 , 1.96
decision: reject Ho
p-value: 0

b.
cohens d value is not exist for this case as sample value a way lessar than population , w

data indicate a significant difference in rated attractiveness when the woman appeared to have a tattoo

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