Plant growth (productivity) is often related to the amount of nitrogen (N) avail
ID: 47470 • Letter: P
Question
Plant growth (productivity) is often related to the amount of nitrogen (N) available in the soils. Consider the following figure:
What is/are the independent variable(s)?
Productivity
Available N
Productivity and available N
Cannot be determined
What is/are the dependent variable(s)?
Productivity
Available N
Productivity
Cannot be determined
What is the most precise description of the relationship between productivity and nitrogen?
Positive
Negative
Productivity = (nitrogen*75.2) ? 88.1
There is no apparent relationship
Is this relationship (if any) statistically significant?
Yes, by a lot
Yes, by a little
No
Cannot be determined
What evidence did you use to determine your answer to the previous question?
Y = (x*75.2) ? 88.1
r squared = 0.91
p < 0.01
visual inspection of the data
An increase in available N of 1 g/m2/yr is predicted to have which of the following effects?
Increase productivity
Decrease productivity by 88.1 g
Increase productivity by 0.91 g
Cannot be determined
The value 75.2 represents what in this example?
Slope
Intercept
Coefficient of variation
Probability of a type-1 error
Available nitrogen explains what percent of the variation in productivity?
75.2
91
0.91
< 0.01
What is this type of statistical analysis called?
Correlation
Regression
t-test
ANOVA
What is the null hypothesis associated with this type of statistical analysis?
Means of x and y are equal
Variances of x and y are equal
No association between x and y
Slope of line y = bx + a is zero
y x.75.2) 88.1 r 0.91 Ps0.01 500 200 100 10 vailable N (g/m2yr)Explanation / Answer
Answer
A. Independent Variable: Available N
B. Dependent Variable: Productivity
C. The relationship between productivity and nitrogen: Positive
D. Statistical significance: Yes, by a little
E. p < 0.01
F. Increased productivity
G. Slope
H. Percent of the variation in productivity: 75.2
I.Type of statistical analysis: Regression