Ecological Methods GE Chp 6Questions
with verified answers.
1 Questions to ask yourself before initiating a research project - Correct Answer Are there spatial or
temporal difference in variable Y? What is the effect of factor X on variable Y? Are the measurements of
variable Y consistent with the predictions of hypothesis H? Using the measurements of variable Y, what
is the best estimate of parameter in model Z?
2 Two types of field experiments - Correct Answer manipulative and natural experiments. Manipulative
experiments alter levels of a predictor variable (or factor), and then measures how one or more
variables respond to these alterations. These results are then used to test cause-and-effect. Advantage
of manipulative experiments: Results of manipulative experiments are used to test hypotheses of cause-
and-effect. You can apply known treatments and quantify their effects. Disadvantages of manipulative
experiments: 1) it is challenging to conduct experiments on large spatial scales; most manipulative
studies are conducted on smaller spatial scales. When experiments are conducted on large spatial
scales, replication is sacrificed. Experiments conducted on small spatial scales may not yield results that
are representative of patterns and processes occurring at larger spatial scales. Natural experiments-An
observational study in which we take advantage of natural variation that is present in the variable of
interest. Advantages-Can be done on large spatial and temporal scales; you can study processes with
'no' manipulations.Disadvantages-In natural experiments, we do not know the direction of cause-and-
effect, and we have not controlled for other variables that surely will differ among the replicates.
3 Types of natural experiments - Correct Answer snapshot and trajectory experiments.
Snapshot experiments - Correct Answer are replicated in space; replication is spatial; each observation
represents a different plot censused at the same time. The advantages of a snapshot experiment are
that it is rapid, and the spatial replicates arguably are more statistically independent of one another.The
disadvantages of snapshot experiments: doesn't account for changes that occur with time.
Trajectory experiments - Correct Answer replication is temporal; each observation represents a different
time. The advantage of a trajectory experiment is that it reveals how ecological systems change through
time.Disadvantages of trajectory experiments: are restricted to a single site and are unreplicated in
space. We don't know if the temporal trajectories described from that site are typical for what we might
find at other sites. Each trajectory is essentially a sample size of one at a given site. The further apart in
time the samples are separated from one another, the more they function as independent replicates.
4) Types of manipulative experiments - Correct Answer press and pulse experiments
with verified answers.
1 Questions to ask yourself before initiating a research project - Correct Answer Are there spatial or
temporal difference in variable Y? What is the effect of factor X on variable Y? Are the measurements of
variable Y consistent with the predictions of hypothesis H? Using the measurements of variable Y, what
is the best estimate of parameter in model Z?
2 Two types of field experiments - Correct Answer manipulative and natural experiments. Manipulative
experiments alter levels of a predictor variable (or factor), and then measures how one or more
variables respond to these alterations. These results are then used to test cause-and-effect. Advantage
of manipulative experiments: Results of manipulative experiments are used to test hypotheses of cause-
and-effect. You can apply known treatments and quantify their effects. Disadvantages of manipulative
experiments: 1) it is challenging to conduct experiments on large spatial scales; most manipulative
studies are conducted on smaller spatial scales. When experiments are conducted on large spatial
scales, replication is sacrificed. Experiments conducted on small spatial scales may not yield results that
are representative of patterns and processes occurring at larger spatial scales. Natural experiments-An
observational study in which we take advantage of natural variation that is present in the variable of
interest. Advantages-Can be done on large spatial and temporal scales; you can study processes with
'no' manipulations.Disadvantages-In natural experiments, we do not know the direction of cause-and-
effect, and we have not controlled for other variables that surely will differ among the replicates.
3 Types of natural experiments - Correct Answer snapshot and trajectory experiments.
Snapshot experiments - Correct Answer are replicated in space; replication is spatial; each observation
represents a different plot censused at the same time. The advantages of a snapshot experiment are
that it is rapid, and the spatial replicates arguably are more statistically independent of one another.The
disadvantages of snapshot experiments: doesn't account for changes that occur with time.
Trajectory experiments - Correct Answer replication is temporal; each observation represents a different
time. The advantage of a trajectory experiment is that it reveals how ecological systems change through
time.Disadvantages of trajectory experiments: are restricted to a single site and are unreplicated in
space. We don't know if the temporal trajectories described from that site are typical for what we might
find at other sites. Each trajectory is essentially a sample size of one at a given site. The further apart in
time the samples are separated from one another, the more they function as independent replicates.
4) Types of manipulative experiments - Correct Answer press and pulse experiments
