Question

A researcher wishes to test whether the mean time for complete metamorphosis in frogs differs with concentration of Atrazine. The researcher establishes three groups of frogs (A, B, C) and raises them from eggs to adults in a controlled laboratory setting. Group A = Control, Group B = 25ppm, Group C = 50 ppm. Run the appropriate analysis. What's the p value? Use the dataset below.

Response	Group
92	A
102	A
156	A
132	A
140	A
89	A
103	A
122	A
140	A
120	A
92	A
102	A
156	A
132	A
140	A
98	A
103	A
122	A
140	A
139	B
144	B
190	B
210	B
187	B
150	B
130	B
129	B
160	B
176	B
139	B
144	B
190	B
210	B
187	B
150	B
130	B
129	B
160	B
210	C
230	C
230	C
209	C
194	C
203	C
195	C
200	C
190	C
199	C
210	C
230	C
229	C
196	C
198	C
206	C
230	C
200	C
190	C

Answer 1

using minitab>stat>Anova>one way anova

we have

One-way ANOVA: Response versus Group

Method

Null hypothesis All means are equal
Alternative hypothesis At least one mean is different
Significance level α = 0.05

Equal variances were assumed for the analysis.

Factor Information

Factor Levels Values
Group 3 A, B, C

Analysis of Variance

Source DF Adj SS Adj MS F-Value P-Value
Group 2 73347 36673.5 74.94 0.000
Error 54 26427 489.4
Total 56 99774

Model Summary

S R-sq R-sq(adj) R-sq(pred)
22.1222 73.51% 72.53% 70.49%

Means

Group N Mean StDev 95% CI
A 19 120.05 22.02 (109.88, 130.23)
B 19 160.74 27.71 (150.56, 170.91)
C 19 207.84 14.68 (197.67, 218.02)

Pooled StDev = 22.1222

P value is 0.000 which is less than 0.05 so we have sufficient evidence to conclude that the mean time for complete metamorphosis in frogs differs with concentration of Atrazine