Question

Here are data from an Oreo comparison taste test done between regular and low-fat Oreo cookies.
Subject 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
Regular 3 7 5 7 8 10 9 6 10 5 9 8 8 8 6 5 6 8 7
Low-fat 6 4 8 8 6 6 5 4 7 7 5 7 6 6 8 7 4 6 5
Use it and R to run
a. A sign test to see if there is a difference in the median taste test rating between regular and
low-fat Oreo cookies.
b. A Wilcoxon signed-ranks test to see if there is a difference in the median taste test rating
between regular and low-fat Oreo cookies.

Answer 1

Solution-

R commands with output--

# Data from an Oreo comparison taste test done between regular and low-fat Oreo cookies.

>

> Regular= c(3,7,5,7,8,10,9,6,10,5,9,8,8,8,6,5,6,8,7)

> Low_fat= c(6,4,8,8,6,6,5,4,7,7,5,7,6,6,8,7,4,6,5)

>

>

> ## Sign Test

>

> d=Regular-Low_fat

> sp=length(d[d>0])

> sn=length(d[d<0])

> n=sp+sn

> P_value=pbinom(sp,n,0.5)

> sp

[1] 13

> P_value

[1] 0.9682159

>

>

> ## Wilcoxon's signed rank test

>

> wilcox.test(Regular,Low_fat,paired = T)

Wilcoxon signed rank test with continuity correction

data: Regular and Low_fat

V = 137, p-value = 0.08888

alternative hypothesis: true location shift is not equal to 0

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