Mathematics, 04.03.2020 04:52 NetherisIsTheQueen

Researchers have observed that rainforest areas next to clear-cuts (less than 100 meters away) have a reduced tree biomass compared to rainforest areas far from clear-cuts. To go further, Laurance et al. (1997) tested whether rainforest areas more distant from the clear-cuts were also affected. They compiled data on the biomass change after clear-cutting (in tons/hectare/year) for 36 rainforest areas between 100 m and several km from clear-cuts. The data are as follows:

-10.8, -4.9, -2.6, -1.6, -3, -6.2, -6.5, -9.2, -3.6, -1.8, -1, 0.2, 0.2, 0.1, -0.3, -1.4, -1.5, -0.8, 0.3, 0.6, 1, 1.2, 2.9, 3.5, 4.3, 4.7, 2.9, 2.8, 2.5, 1.7, 2.7, 1.2, 0.1, 1.3, 2.3, 0.5

Test whether there is a change in biomass of rainforest areas following clear-cutting.

Answers: 3

Show answers

Answers

Answer from: hwhite41

$t=\frac{-0.506-0}{\frac{3.557}{\sqrt{36}}}=-0.854$

$p_v =2*P(t_{(35)}$

If we compare the p value and the significance level assumed $\alpha=0.05$ we see that $p_v\alpha$ so we can conclude that we have enough evidence to FAIL to reject the null hypothesis, and we can conclude that we don't have a significant change at 5% of signficance.

Step-by-step explanation:

Data given and notation

-10.8, -4.9, -2.6, -1.6, -3, -6.2, -6.5, -9.2, -3.6, -1.8, -1, 0.2, 0.2, 0.1, -0.3, -1.4, -1.5, -0.8, 0.3, 0.6, 1, 1.2, 2.9, 3.5, 4.3, 4.7, 2.9, 2.8, 2.5, 1.7, 2.7, 1.2, 0.1, 1.3, 2.3, 0.5

We can calculate the mean and deviation with the following formulas:

$\bar X = \frac{\sum_{i=1}^n X_i}{n}$

$s = \sqrt{\frac{\sum_{i=1}^n (X_i -\bar X)^2)}{n-1}}$

And we obtain:

$\bar X=-0.506$ represent the sample mean

s=3.557 represent the sample standard deviation

n=36 sample size

$\mu_o =0$ represent the value that we want to test

$\alpha=0.05$ represent the significance level for the hypothesis test. (assumed)

t would represent the statistic (variable of interest)

p_v represent the p value for the test (variable of interest)

State the null and alternative hypotheses.

We need to conduct a hypothesis in order to check if there is a change in biomass of rainforest areas following clear-cutting, the system of hypothesis are :

Null hypothesis: $\mu = 0$

Alternative hypothesis: $\mu \neq 0$

Since we don't know the population deviation, is better apply a t test to compare the actual mean to the reference value, and the statistic is given by:

$t=\frac{\bar X-\mu_o}{\frac{s}{\sqrt{n}}}$ (1)

t-test: "Is used to compare group means. Is one of the most common tests and is used to determine if the mean is (higher, less or not equal) to an specified value".

Calculate the statistic

We can replace in formula (1) the info given like this:

$t=\frac{-0.506-0}{\frac{3.557}{\sqrt{36}}}=-0.854$

P-value

First we need to calculate the degrees of freedom given by:

df=n-1=36-1=35

Since is a two tailed test the p value would be:

$p_v =2*P(t_{(35)}$

Conclusion

Answer from: Quest

i need on these three questions. find standard form equation of line perpendicular to y = (2/3)x - 8 that goes through the point

the equation of a line is -6x-2y=-18 what is the x 3 answers sep 21, 2015

finding the critical point for f(x,y)=(x^2)*y+y^3 1 answer mar 10, 2013

Another question on Mathematics

Mathematics, 21.06.2019 14:30

What is the value of x in the figure below? if necessary, round your answer to the nearest tenth of a unit. 12 d 4 b оа. 3.1 ов. 6.9 ос. 4 od. 12

Answers: 2

Answer

Mathematics, 21.06.2019 14:50

Eight people were asked what the balance of their savings account at the beginning of the month was and how much it increased or decreased by the end of the month. create a scatter plot that represents the data that is shown in the table. the x-axis represents the beginning balance in thousands of dollars and the y-axis represents the change in the savings account in hundreds of dollars. name beginning balance (in thousands of dollars) change in savings account (in hundreds of dollars) jimmy 5 3 kendra 4 7 carlos 5 4 yolanda 3 1 shawn 2 5 laura 3 2 andy 5 6 georgia 4 3

Answers: 1

Answer

Mathematics, 21.06.2019 17:40

Follow these steps using the algebra tiles to solve the equation −5x + (−2) = −2x + 4. 1. add 5 positive x-tiles to both sides and create zero pairs. 2. add 4 negative unit tiles to both sides and create zero pairs. 3. divide the unit tiles evenly among the x-tiles. x =

Answers: 2

Answer

Mathematics, 21.06.2019 18:00

Sarah used her calculator to find sin 125 degrees. she wrote down sin sin125 degrees.57. how could sarah recognize that her answer is incorrect?

Answers: 1

Answer

You know the right answer?

Researchers have observed that rainforest areas next to clear-cuts (less than 100 meters away) have...

Questions