Biostats quiz 3

Plot A and B were made with the same data, but the variables were plotted on different axes in each plot. If we calculated the correlation coefficient (r) for each plot, you would expect:

Would be exactly the same for both plots

When creating a scatterplot to go along with a simple linear regression analysis

the independent variable should be on the x six and the dependent variable should be on the y axis

When creating a scatterplot to go along with a regression analysis

The explanatory variable should be on the x-axis, and the response should be on the y-axis

Plot A and B were made with different data sets. If we calculated the correlation coefficient (r) for each plot, which r value would be closer to 0?

A

Plots A and B were made with different data sets. Guess the two correlation coefficients (r):

Plot a: -0.85,-0.80 to -0.90. Plot b: 0.99 to 1.00

Plot A and B were made with different data sets. Pick the most accurate statement.

?

Plot A and B were made with different data sets. If we calculated the correlation coefficient (r) for each plot, which r value would be closer to 1?

B

Plot A and B were made with different data sets. If we calculated the regression R-squared value for each plot, which R-squared value would be closer to 1?

A

Plot A and B were made with different data sets. If we calculated the regression R-squared value for each plot, which answer appears to be most accurate:

A

Plot A and B were made with different data sets. If we fit a simple linear regression line to the data in each plot, which statement appears to be most appropriate:

?

Plot A and B were made with different data sets. If we fit a simple linear regression line to the data in each plot, which answer appears to be most accurate:

?

What is the rate described by this regression line equation?

0.22 mm per year

What is the y-intercept described by this regression line equation?

55.9 mm

If you were interested in using the given equation to predict ear length in a population, what would be the appropriate age range in which to make those predictions?

30 to 95 years old

Dr. Bobich (CPP Biological Sciences Department) has a burning desire to be able to predict the heights of trees on CPP campus by using their trunk diameter. In order to do this he first goes out on a Saturday, randomly selects 83 trees, and measures the height and diameters of each of them. He then would need to run what type of analysis using these data in order to accomplish this?

Dr. Questad (CPP Biological Sciences Department) wants to be able to determine if there is a relationship between the abundance of native plant species and invasive plant species in the Voorhis Ecological Reserve on CPP campus. During her lunch break, she goes out to the Voorhis and randomly samples 30 plots (1 m-sqrd each) of habitat. She counted all native species as "natives" and all invasive species as "invasives." What type of analysis would she need to run on the data in order to accomplish this (note: she just wants to see if there is any relationship between the two variables at this early stage in the research, not make predictions)?

Dr. Questad (CPP Biological Sciences Department) wants to be able to predict if the height of black mustard is affected by the amount of light available to it in the field. During her lunch break, she went out to the Lyle Center and randomly sampled the height of 30 mustard plants growing in the open. She also measured the strength of light available for each of those plants. What type of analysis would she need to run on these data in order to answer her question?

Dr. Bobich (CPP Biological Sciences Department) has a burning desire to determine if there is a relationship between the photosynthetic rate of Oak leaves and the size of the leaves in the Voorhis Ecological Reserve found on CPP campus, although he doesn't suspect a cause-effect relationship at this early stage in the research. In order to do this he first goes out in his free

time on a Sunday, randomly selects a leaf from each of 30 trees, and measures both the

photosynthetic rate with his LI 6800 portable photosynthesis system and the surface area of

each leaf. He then would need to run what type of analysis using these data in order to

accomplish this?

When creating a scatterplot to go along with a simple linear regression analysis

Which of the following statements about regression R-squared values is FALSE:

For the data presented above, which would you expect to have a larger R² value?

B

For the data above, in which regression equation does Fecundity increase at a greater rate with changes in Wing Length?

B

Which species (plot A or B) has a lower predicted fecundity at a wing-length of 2.2 mm?

B

Which species (plot A or B) has a greater variability in fecundities for a given wing-length?

B

Based on the analysis presented above pick the best answer:

Which species (graph A or B) has a higher slope value?

B

Does there seem to be a relationship between variables X and Y?

no

If you were to draw a regression line fit to data presented above, what would the expect the slope of the line to be?

close to zero or slightly negative

In the graph above, what would be an appropriate estimate of the correlation coefficient (r)?

0