Question

6. The pathogen Phytophtlora capsica causes bell peppers to wilt and die. Because bell peppers are an important commercial crop, this disease has undergone a great deal of agricultural research. It is thought that too much water aids the spread of the pathogen. Two fields are under study. The first step in the research project is to compare the mean soil water content (% water/cm of soil) for the two fields so random and independent samples of soil cores were taken from field A and from field B. Use the output below to test at the 1% significance level and determine if field B, on average, has a lower soil water content that field A. Assume normality. Group Field A Mean 12.52857 10.76875 Std. Dev. 2.394 2.401 Std. Error 0.6398 Field B 0.6003 If Variances Are Df Pvalue Equal 2.005 0.0273 28 -2.005 -2.006 0.0273 Not Equal 27.49 0.0274 a. Can we assume equal population variances? Explain. (3 points) b. Conduct the test. (5 points) H. Conclusion

Answer 1

Solution:

Std. Error Std. Dev Can we assume equal population variances? Explain. (3 points) Group Mean а. Field A 12.52857 14 2.394 0.6398 We can apply Levene's test to see if we can assume equal population variances Field B 16 10.76875 2.401 0.6003 2.4012 F = 2.3942 =1.01 p-value 0.5009 Since the p-value is greater than the significance level, therefore we can assume equal population variances Conduct the test (5 points) H If Variances Are Df Pvalue Н. - И, <и. Еqual -2.005 28 0,0273 Not Equal -2.006 27.49 0.0274 Conclusion Since the p-value is greater than the significance level 0.01, we, therefore fail to reject the null hypothesis and conclude that there is not sufficient evidence to support the claim that field B has on average lower soil water content than that field A.