Question

A consumer preference study compares the effects of three different bottle designs (A, B, and C) on sales of a popular fabric softener. A completely randomized design is employed. Specifically, 15 supermarkets of equal sales potential are selected, and 5 of these supermarkets are randomly assigned to each bottle design. The number of bottles sold in 24 hours at each supermarket is recorded. The data obtained are displayed in the following table.

Bottle Design Study Data
A			B			C
	13			34			26
	17			31			23
	13			34			28
	14			32			27
	16			30			26

  

The Excel output of a one-way ANOVA of the Bottle Design Study Data is shown below.

SUMMARY
Groups	Count	Sum	Average	Variance
Design A	5	73	14.6	3.3
Design B	5	161	32.2	3.2
Design C	5	130	26.0	3.5

ANOVA
Source of Variation	SS	df	MS	F	P-Value	F crit
Between Groups	796.9333	2	398.4667	119.54	3.23E-06	3.88529
Within Groups	40.0	12.0	3.3333
Total	836.9333	14

Find a 95 percent confidence interval for each of the treatment means μ_A, μ_B, and μ_C. Interpret these intervals. (Round your answers to 2 decimal places. Negative amounts should be indicated by a minus sign.)

Confidence interval

μA: [  ,  ]

μB: [  ,  ]

μC: [  ,  ]

Answer 1

Answer: A consumer preference study compares the effects of three different bottle designs (A, B, and C) on sales of a popular fabric softener. A completely randomized design is employed. Specifically, 15 supermarkets of equal sales potential are selected, and 5 of these supermarkets are randomly assigned to each bottle design. The number of bottles sold in 24 hours at each supermarket is recorded. The data obtained are displayed in the following table.

Solution: