Hypothesis: The distribution of the insect larvae is affected by the environmental conditions of the pond.
Variable: Environmental conditions of the pond
Field/Laboratory Procedures:
1. Collect water samples from both ponds and analyze for environmental conditions such as pH, temperature, dissolved oxygen, and nutrient levels.
2. Collect insect larvae samples from both ponds and analyze for species composition.
3. Compare the environmental conditions of the two ponds to the species composition of the insect larvae.
Data Collection:
1. Record the environmental conditions of the two ponds.
2. Record the species composition of the insect larvae in each pond.
Possible Results:
The results of the experiment could show that the environmental conditions of the two ponds are different, and that this difference is responsible for the observed distribution of the insect larvae. Alternatively, the results could show that the environmental conditions of the two ponds are similar, and that some other factor is responsible for the observed distribution of the insect larvae.
I am having trouble with this assignment. Please help!
Larvae of a certain insect are found in pond but not in pond B. Design a controlled experiment that would help explain the observed distributio of these insect larvae. Be sure to include the following in your design.
a) formulate a hypothesis
b) identify the variable that will be manipulated
c) outline the gield and/or laboratory procedures that will be followed. Describe what data you will collect
d) discuss the possible results and relate them to the distribution of the insect
Doing archival research about insect larvae in ponds should give you some idea about what hypothesis you want to generate.
Since this is not my area of expertise, I searched Google under the key words "larvae ponds" to get these possible sources:
http://www.certifiedaquascapecontractor.com/ponds.php
http://www.ecochem.com/resource_mosquito.html
http://www.penobscotswcd.org/publications/insects.pdf
You might want to limit your hypothesis to a particular species.
Although the additional information below applies to constructing human experiments, they may help you to design your experiment.
An independent variable is the potential stimulus or cause, usually directly manipulated by the experimenter, so it could also be called a manipulative variable.
A dependent variable is the response or measure of results.
Extraneous variables — other than the independent variable — potentially can affect the dependent variable, so they must be controlled. If possible, you try to keep them constant between the experimental and control group.
The experimental group receives the independent variable.
The control group is similar to experimental, except it does not receive the independent variable. Extraneous variables are balanced between experimental and control groups.
Types of experiments
1. Single blind gives the control group a placebo — a substance that is inert, it has no physical effect. Subjects don't know if they are in experimental or control group to reduce placebo effect, a change in behavior solely due to believing that you are getting the independent variable.
2. Double blind keeps both subjects and experimenter ignorant of group setup. Distribution of the independent variable and placebo is controlled by third party. This controls for experimenter bias and self-fulfilling prophecy. This means that experimenters with particular expectations are likely to consciously or unconsciously to bias the experiment and influence it to conform to their expectations.
As an example, suppose you want to find out if fluorides reduce dental cavities. You would find two groups, trying to control the extraneous variables. Extraneous variables are found by surveying previous research in the area. In this case, you would match the groups in terms of previous history of cavities, diet and dental hygiene habits including how and how often they brush their teeth.
The experimental group would get toothpaste with the independent variable, the fluoride, while the control group would not have the fluoride in their toothpaste. The toothpaste without the fluoride would be the placebo.
The dependent variable would be the number of cavities after participating in the experiment for a time. The dependent variable indicates the results, but it is not the results. At the end of the experiment, both groups could have no change in cavities or one of the groups could have a greater reduction in cavities. (Of course, if the fluoride increased cavities, you wouldn't want to use it.) All of these varied results would be indicated in terms of the dependent variable.
If only the subjects do not know who is getting the fluoride, it is a single blind experiment. If both the subjects and experimenter do not know, it is a double blind.
I hope this helps. Thanks for asking.
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