Question

An investigator conducts an experiment involving the effects of three levels of a drug on memory. 12 subjects are randomly assigned to one of three conditions (0mg, 15mg, 30mg). A different drug level is administered in each condition. Memory is measured 10 minutes after each subject receives the drug. The following scores are recorded. The higher the score, the better the memory.

0mg Drug 6, 10, 8, 11

15mg Drug: 9, 7, 9, 11

30mg Drug: 13, 15, 14, 19

A. SS within =

B. SS between =

C. df within =

D. df between =

E. df total =

F.MS within =

G. MS between =

H. F obt =

I. Using α = 0.05, Fcrit =

J. Using α = 0.05, what do you conclude?

Answer 1

Excel output:

Anova: Single Factor
SUMMARY
Groups	Count	Sum	Average	Variance
0mg Drug	4	35	8.75	4.91667
15mg Drug	4	36	9	2.66667
30mg Drug	4	61	15.25	6.91667
ANOVA
Source of Variation	SS	df	MS	F	P-value	F crit
Between Groups	108.5	2	54.25	11.2241	0.0036	4.2565
Within Groups	43.5	9	4.8333
Total	152	11

A. SS within =43.5

B. SS between =108.5

C. df within =9

D. df between =2

E. df total =11

F.MS within =4.8333

G. MS between =54.25

H. F obt =11.2241

I. Using α = 0.05, Fcrit =4.2565

J. Since F obt>Fcrit so there is sufficient evidence to conclude that mean scores of three levels of Drug are not all equal.