The presence of predators has been hypothesized to induce changes in behavior an
ID: 47456 • Letter: T
Question
The presence of predators has been hypothesized to induce changes in behavior and morphology of prey. Consider the graph below comparing activity levels of snails reared either in the presence or absence of their crab predator. Analysis of variance (ANOVA) found that F1,10 = 6.12; and p = 0.043. Answer the following questions:
What is/are the independent variable(s)?
Predator presence/ absence
Predator activity level
Prey presence/ absence
Pretty activity level
What is/are the dependent variable(s)?
Predator presence/ absence
Predator activity level
Prey presence/absence
Prey activity level
The independent variable(s) is/are
Numerical and continuous
Numerical and discrete
Categorical and nominal
Categorical and ordianl
The dependent variable(s) is/are
Numerical and continuous
Numerical and discrete
Categorical and nominal
Categorical and ordianl
Which treatment would you consider to be the ?control??
No predator; no prey
No predator; prey
Predator; no prey
Predator; prey
What does the height of each bar represent, per group?
Mean activity level
Maximum activity level
Summed activity level
Variance in activity level
What is the null hypothesis for this experiment?
Equal mean activity in the two groups
Equal variance in activity in the groups
More mean activity with no predators
More variable activity with no predators
What is the probability of getting an F value of 6.12 if the null hypothesis is true?
0.05
0.043
4.3
0.95
Given the reported statistical results, would the null hypothesis be rejected with an ? = 0.05 or 0.01?
Yes at both 0.05 and 0.01
Yes at 0.05, but no at 0.01
No at both 0.05 and 0.01
Cannot be determined
Given the reported statistical results, to what degree is the proposed ecological hypothesis supported?
Strongly
Weakly
It is not
Cannot be determined
Explanation / Answer
1.
The independent variables are
Predator presence/absence and Prey presence/absence
2.
The dependent variables are
Predator activity level and Prey activity level ( depends on presence/absence of predator and prey)
3.
The independent variables are Numerical and discrete ( because can count the number of predators and preys)
4.
The dependent variables are Categorical and ordinal (because activity can be high , medium or low hence clear ordering is there )
5.
The treatment for control would be Predator,Prey ( because the activity level of prey increase if predator present)
6.
The height of each bar represent mean activity level
7.
Null hypothesis is equal variance in activity in the groups
8.
P of getting F value of 6.12 is 0.05
9.
At 0.05 it will be rejected ( p < 0.05) but at 0.01 it won't be rejected (p>0.01)
10.
It will be weakly supported because the null hypothesis will be false for different variance of the data
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