Suppose that the scholarship committee of a school would like to ensure that eac

Question

Suppose that the scholarship committee of a school would like to ensure that each of the three graders (A, B, C) is using the same grading scale, as otherwise the students aren't being treated equally. Suppose we have the following results for 27 tests from the three graders:

A

4

3

3

2

4

2

3

5

5

B

3

4

5

3

3

3

3

2

4

C

3

5

2

3

5

5

5

3

3

Test the hypothesis that the three graders have the same grading scale using one way ANOVA. Note that the data is for 27 independent tests.

By using R

A

4

3

3

2

4

2

3

5

5

B

3

4

5

3

3

3

3

2

4

C

3

5

2

3

5

5

5

3

3

Explanation / Answer

> a <- c(4,3,3,2,4,2,3,5,5)
> b <- c(3,4,5,3,3,3,3,2,4)
> c <- c(3,5,2,3,5,5,5,3,3)
> grader <- data.frame(grader = rep(c("a","b","c"),each = 9), score = c(a,b,c))
> res.aov <- aov(score ~ grader, data = grader)
> summary(res.aov)
Df Sum Sq Mean Sq F value Pr(>F)
grader 2 0.963 0.4815 0.416 0.664
Residuals 24 27.778 1.1574

Since the result is not significant, we conclude that the 3 graders have the same grading scale

Related Questions

Navigate

• Browse (All)
• Browse S
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.