Does burning the native prairie grass big bluestem (Andropogon gerardii) in the

Question

Does burning the native prairie grass big bluestem (Andropogon gerardii) in the fall, compared to mowing this grass in the fall, increase the number of culms (grass flowering stems) next spring? You randomly mark out 13 one square meter plots in a prairie restoration project in an area that is virtually c exclusively big bluestem. Each plot has divided in half. In the fall 13 one half plots were carefully burned while the other matched 13 one half plots were mowed In the early summer of the following year the number of culms were counted for all half plots with the following results: Since the data are widely scattered and sample site is quite small, you decide to use the Sign Test. Therefore check to see if the average number of culms was statistically greater for the burned half plots compared to the mowed half plots. Use the Sign Test and use the usual five step procedure at Alpha = 0.05

Explanation / Answer

Let X and Y be the number of culms in burned half plots and in mowed half plots respectively. We want to test whether the median of both the population is same or not. We will carry out non-parametric wilcoxon signed rank test to validate that. Let Mu be the median of the distribution of X-Y. We will test : H0 : Mu =0 vs H1: Mu ~= 0

We will carry out wilcoxon sign rank test in R.

Code:

burn<-c(29,23,18,29,26,22,30,18,21,20,31,38,27)
mowed<-c(28,20,16,33,26,19,29,17,20,22,31,30,25)
wilcox.test(burn,mowed,paired=TRUE,exact=FALSE,
alternative ="two.sided",correct=FALSE)

Output:

Wilcoxon signed rank test

data: burn and mowed
V = 50, p-value = 0.1278
alternative hypothesis: true location shift is not equal to 0

So as the p-value is greater than 0.05, the significance level, we will fail to reject H0 and conclude that average number of culms was statistically equal for burned half plots and mowed half plots.

Related Questions

Navigate

• Browse (All)
• Browse D
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.