Ecological Methods Chp 3 KH Questions
with verified answers.
1 Why do ecologists prefer manipulative experiments? What alternatives exist to this type of
experiment? - Correct Answer Control which variables you are testing and it is easier to replicate. It tries
to determine if correlation is due to causality or not. Alternatives include observations and model
building.
2 What is a good manipulative experiment? What are the four criteria for a good experiment? - Correct
Answer Change few variables with many replications of each.Make necessary controls, use correct scale,
understand your target audience, and keep unbiased.
3 What are controls and why do we need them? Give examples of appropriate controls. - Correct
Answer Controls are your baseline. What you compare your experimental group to.For Crayfish
experiment, the shrimp diet without carophyll pink is the control.
4 Why are not all experimental treatments of the same value? What can you do to ensure you have
effective treatments? Examples? - Correct Answer Some treatments may change underlying variables
that are not accounted for. If we were to put plants in a greenhouse with automatic sprayers in rows
separated by treatment, and one of the sprayers was faulty, that treatment would be altering one of the
controls. What if one side of the greenhouse received more sunlight? These are all supplemental factors
that can be changed by the attempt to only change a small amount of variables. To prevent these
occurrences, randomization of placement of the treatments and larger sample sizes could be taken into
account.
5 What is a replicate? Why do ecologists use replication? What are some examples of good and bad
replicates? - Correct Answer A replicate is a single observation (in our experiment a single crayfish is a
single replicate - we have 79). Replication is a way to further ensure that your data is representative of
the populations. It provides more observations under the same controls. It attempts to eliminate or
lower the effect of outliers on the results of the experiment as well as the possibility of just observing
random chance.
6 What is an appropriate sample size for an experiment? What factors are important to consider when
determining your sample size? Discuss the idea of a tradeoff between scale and replication. - Correct
Answer This all depends on the question being asked in the experiment. It's a question of qualitative
measurements vs. quantitative measurements. This can also come back to the idea of funding and time
restraints that the experiments are under. Statisticians suggest that you collect preliminary data in order
to determine the sample size needed to answer your question. The larger number of replicates, the
with verified answers.
1 Why do ecologists prefer manipulative experiments? What alternatives exist to this type of
experiment? - Correct Answer Control which variables you are testing and it is easier to replicate. It tries
to determine if correlation is due to causality or not. Alternatives include observations and model
building.
2 What is a good manipulative experiment? What are the four criteria for a good experiment? - Correct
Answer Change few variables with many replications of each.Make necessary controls, use correct scale,
understand your target audience, and keep unbiased.
3 What are controls and why do we need them? Give examples of appropriate controls. - Correct
Answer Controls are your baseline. What you compare your experimental group to.For Crayfish
experiment, the shrimp diet without carophyll pink is the control.
4 Why are not all experimental treatments of the same value? What can you do to ensure you have
effective treatments? Examples? - Correct Answer Some treatments may change underlying variables
that are not accounted for. If we were to put plants in a greenhouse with automatic sprayers in rows
separated by treatment, and one of the sprayers was faulty, that treatment would be altering one of the
controls. What if one side of the greenhouse received more sunlight? These are all supplemental factors
that can be changed by the attempt to only change a small amount of variables. To prevent these
occurrences, randomization of placement of the treatments and larger sample sizes could be taken into
account.
5 What is a replicate? Why do ecologists use replication? What are some examples of good and bad
replicates? - Correct Answer A replicate is a single observation (in our experiment a single crayfish is a
single replicate - we have 79). Replication is a way to further ensure that your data is representative of
the populations. It provides more observations under the same controls. It attempts to eliminate or
lower the effect of outliers on the results of the experiment as well as the possibility of just observing
random chance.
6 What is an appropriate sample size for an experiment? What factors are important to consider when
determining your sample size? Discuss the idea of a tradeoff between scale and replication. - Correct
Answer This all depends on the question being asked in the experiment. It's a question of qualitative
measurements vs. quantitative measurements. This can also come back to the idea of funding and time
restraints that the experiments are under. Statisticians suggest that you collect preliminary data in order
to determine the sample size needed to answer your question. The larger number of replicates, the
