A strain of genetically engineered cotton, known as Bt cotton, is resistant to certain insects, which results in larger yields of cotton. Farmers in northern China have increased the number of acres planted in Bt cotton. Because Bt cotton is resistant to certain pests, farmers have also reduced their use of insecticide. Scientists in China were interested in the long‑term effects of Bt cotton cultivation and decreased insecticide use on insect populations that are not affected by Bt cotton. One such insect is the mirid bug. Scientists measured the number of mirid bugs per 100 plants and the proportion of Bt cotton planted at 38 locations in northern China for the 12‑year period from 1997–2008. The scientists reported this regression analysis: number of mirid bugs per 100 plants=0.54+6.81× Bt cotton planting proportion ?2=0.90, ?<0.0001 What does the slope b=6.81 say about the relation between Bt cotton planting proportion and number of mirid bugs per 100 plants? - Scientists estimate that each additional 10% increase in the percentage of Bt cotton plants results in an increase of 6.81 mirid bugs per 100 plants. - Scientists estimate that each additional 100% increase in the percentage of Bt cotton plants results in an increase of 6.81 mirid bugs per 100 plants. - Scientists estimate that each additional 1% increase in the percentage of Bt cotton plants results in an increase of 6.81 mirid bugs per 100 plants. - Scientists estimate that each additional 50% increase in the percentage of Bt cotton plants results in an increase of 6.81 mirid bugs per 100 plants. (b) What does ?2=0.90 add to the information given by the equation of the least‑squares line? - The regression model explains 45%45% of the variability in mirid bug density. - The regression model explains 90%90% of the variability in mirid bug density. - The regression model explains 10%10% of the variability in mirid bug density. - The regression model explains 30%30% of the variability in mirid bug density. What does ?<0.0001 tell you? - It is not strong evidence of a of linear relationship between the proportion of Bt cotton and the density of mirid bugs. - It is strong evidence of a negative linear relationship between the proportion of Bt cotton plants and the density of mirid bugs. - It is strong evidence of a positive linear relationship between the proportion of Bt cotton plants and the density of mirid bugs. - It is strong evidence of some type of linear relationship between the proportion of Bt cotton and the density of mirid bugs. (d) Does the large value of ?^2 and the small P-value indicate that increasing the proportion of acres planted in Bt cotton causes an increase in mirid bugs? - No. We may conclude that increased use of Bt cotton plants is associated with an increase in mirid bugs, but it seems plausible that a reduced use of pesticides instead of more Bt cotton plants is the reason for this increase. - No. The large value of ?^2 and the small P‑value do not indicate that increased use of Bt cotton plants is associated with an increase in mirid bugs. - Yes. We may conclude that increased use of Bt cotton plants causes an increase in mirid bugs.

A strain of genetically engineered cotton, known as Bt cotton, is resistant to certain insects, which results in larger yields of cotton. Farmers in northern China have increased the number of acres planted in Bt cotton. Because Bt cotton is resistant to certain pests, farmers have also reduced their use of insecticide. Scientists in China were interested in the long‑term effects of Bt cotton cultivation and decreased insecticide use on insect populations that are not affected by Bt cotton. One such insect is the mirid bug. Scientists measured the number of mirid bugs per 100 plants and the proportion of Bt cotton planted at 38 locations in northern China for the 12‑year period from 1997–2008. The scientists reported this regression analysis: number of mirid bugs per 100 plants=0.54+6.81× Bt cotton planting proportion ?2=0.90, ?<0.0001 What does the slope b=6.81 say about the relation between Bt cotton planting proportion and number of mirid bugs per 100 plants? - Scientists estimate that each additional 10% increase in the percentage of Bt cotton plants results in an increase of 6.81 mirid bugs per 100 plants. - Scientists estimate that each additional 100% increase in the percentage of Bt cotton plants results in an increase of 6.81 mirid bugs per 100 plants. - Scientists estimate that each additional 1% increase in the percentage of Bt cotton plants results in an increase of 6.81 mirid bugs per 100 plants. - Scientists estimate that each additional 50% increase in the percentage of Bt cotton plants results in an increase of 6.81 mirid bugs per 100 plants. (b) What does ?2=0.90 add to the information given by the equation of the least‑squares line? - The regression model explains 45%45% of the variability in mirid bug density. - The regression model explains 90%90% of the variability in mirid bug density. - The regression model explains 10%10% of the variability in mirid bug density. - The regression model explains 30%30% of the variability in mirid bug density. What does ?<0.0001 tell you? - It is not strong evidence of a of linear relationship between the proportion of Bt cotton and the density of mirid bugs. - It is strong evidence of a negative linear relationship between the proportion of Bt cotton plants and the density of mirid bugs. - It is strong evidence of a positive linear relationship between the proportion of Bt cotton plants and the density of mirid bugs. - It is strong evidence of some type of linear relationship between the proportion of Bt cotton and the density of mirid bugs. (d) Does the large value of ?^2 and the small P-value indicate that increasing the proportion of acres planted in Bt cotton causes an increase in mirid bugs? - No. We may conclude that increased use of Bt cotton plants is associated with an increase in mirid bugs, but it seems plausible that a reduced use of pesticides instead of more Bt cotton plants is the reason for this increase. - No. The large value of ?^2 and the small P‑value do not indicate that increased use of Bt cotton plants is associated with an increase in mirid bugs. - Yes. We may conclude that increased use of Bt cotton plants causes an increase in mirid bugs.

MATLAB: An Introduction with Applications

6th Edition

ISBN:9781119256830

Author:Amos Gilat

Publisher:Amos Gilat

Chapter1: Starting With Matlab

Section: Chapter Questions

Problem 1P

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Question

number of mirid bugs per 100 plants=0.54+6.81× Bt cotton planting proportion

?2=0.90, ?<0.0001

What does the slope b=6.81 say about the relation between Bt cotton planting proportion and number of mirid bugs per 100 plants?

- Scientists estimate that each additional 10% increase in the percentage of Bt cotton plants results in an increase of 6.81 mirid bugs per 100 plants.

- Scientists estimate that each additional 100% increase in the percentage of Bt cotton plants results in an increase of 6.81 mirid bugs per 100 plants.

- Scientists estimate that each additional 1% increase in the percentage of Bt cotton plants results in an increase of 6.81 mirid bugs per 100 plants.

- Scientists estimate that each additional 50% increase in the percentage of Bt cotton plants results in an increase of 6.81 mirid bugs per 100 plants.

(b) What does ?2=0.90 add to the information given by the equation of the least‑squares line?

- The regression model explains 45%45% of the variability in mirid bug density.

- The regression model explains 90%90% of the variability in mirid bug density.

- The regression model explains 10%10% of the variability in mirid bug density.

- The regression model explains 30%30% of the variability in mirid bug density.

What does ?<0.0001 tell you?

- It is not strong evidence of a of linear relationship between the proportion of Bt cotton and the density of mirid bugs.

- It is strong evidence of a negative linear relationship between the proportion of Bt cotton plants and the density of mirid bugs.

- It is strong evidence of a positive linear relationship between the proportion of Bt cotton plants and the density of mirid bugs.

- It is strong evidence of some type of linear relationship between the proportion of Bt cotton and the density of mirid bugs.

(d) Does the large value of ?^2 and the small P-value indicate that increasing the proportion of acres planted in Bt cotton causes an increase in mirid bugs?

- No. We may conclude that increased use of Bt cotton plants is associated with an increase in mirid bugs, but it seems plausible that a reduced use of pesticides instead of more Bt cotton plants is the reason for this increase.

- No. The large value of ?^2 and the small P‑value do not indicate that increased use of Bt cotton plants is associated with an increase in mirid bugs.

- Yes. We may conclude that increased use of Bt cotton plants causes an increase in mirid bugs.

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