Question

Four different paints are advertised as having the same drying time. To check the manufacturers' claims, five samples were tested for each of the paints. The time in minutes until the paint was dry enough for a second coat to be applied was recorded. Conduct an analysis to see whether the mean drying time is the same for each type of paint.

Paint 1	Paint 2	Paint 3	Paint 4
128	144	133	150
137	133	132	142
135	138	137	148
124	146	136	140
145	130	131	153

What is the test statistic value from your analysis?

Answer 1

Solution

We will find the test statistic using excel by performing One Way Anova

Anova: Single Factor
SUMMARY
Groups	Count	Sum	Average	Variance
Paint 1	5.0000	669.0000	133.8000	66.7000
Paint 2	5.0000	691.0000	138.2000	47.2000
Paint 3	5.0000	669.0000	133.8000	6.7000
Paint 4	5.0000	733.0000	146.6000	29.8000
ANOVA
Source of Variation	SS	df	MS	F	P-value	F crit
Between Groups	546.2000	3.0000	182.0667	4.8422	0.0139	3.2389
Within Groups	601.6000	16.0000	37.6000
Total	1147.8000	19.0000

the test statistic value F = 4.8422

P-value = 0.0139

Conclusion : Here P-value = 0.0139 < 0.05 level of significance so we reject the null hypothesis and conclude that the mean drying time is not same for each type of paint.