COMPETITION EXPERIMENT: DATA ANALYSIS AND POWER-POINT PRESENTATION
Data Analysis and Summary: The design of your experiment will determine how you summarize your data. You should calculate the average size of the plants for each species under intraspecific competition only, interspecific competition, and under the two different environmental conditions. Then you can answer specific questions by statistically testing specific contrasts such as: (1) how did fertilizer (or whatever) impact species A (or B)? --run a t-test comparing the average size of A under intraspecific competition under high and low fertilizer. (2) Which species was the stronger interspecific competitor? --compare the average size of one individual of species A under low nutrients and growing with other A's to the average size of one individual of A under low nutrients with B's--note that the only thing that varies here is who the A competes against, another A or a B. If A is bigger when competing against B than against another A, then A is a stronger interspecific competitor. If A was the stronger interspecific competitor, you would expect B to be smaller when competing against A than against other Bs. (3) Did the outcome of interspecific competition depend on the environmental condition?--run the same comparison as in (2) for the high nutrient condition and visually determine if the patterns are the same. If they are, then the outcome of interspecific competition remains the same, and if you get a different pattern, then the outcome is different. You can see that what you have to do is allow only one thing to vary between your contrasts. You should run a t-test and compare the means and their standard errors to decide if they differ significantly. You can also work with total pot weight if you wish. Remember, the law of constant yield predicts that it should not matter how many plants there are per pot, the total pot weight should be constant. Remember to not make p<0.05 a strict cut-off for significance since we have small sample size—also use your mean and standard error to compare treatments. Make clear data summaries (i.e., bar graphs with standard error bars are easy to interpret).
Presentation: Turn in a copy of your presentation--it can be a black and white print with multiple slides per sheet.
You will be graded as follows:
1. introduction (5pts): do you present appropriate background on the species you used and the questions you addressed. Do you cite appropriate references.
2. methods (5pts): do you describe your methods clearly, without unnecessary details.
3. results (12.5pts): more points here, as there is more to do. You will need clear and accurate figures (bar graphs with standard error that make appropriate contrasts). You need t-tests to compare means. Refer to the format in your lab manual on preparing a lab report for background on presenting data results (section 1c).
4. conclusion (12.5pts): Explain what your results mean in terms of what you know about the species, competition, and environmental conditions. You will need to refer to your text and web resources that must be clearly referenced (written out in presentation) to explain the patterns you find. Making reference to the material you have learned in this course in explaining your results will gain you points.
5. questions (5pts): do you ask a reasonable question about someone else's presentation.
Presentation tips
1. use large font sizes (at least 24)
2. use light or white backgrounds to graphs with dark lines and text
3. use color logically--if high nutrients are dark bars in one figure, make sure they are in the next one too.
3. talk loud and clear, and don't start talking fast to get it over sooner
4. explain your figures--start with the axes, and explain what each is, then move to the bars. We will want to have time to make sure we understand the data being presented.
Here are some web links to oral and poster presentations.
http://www.kumc.edu/SAH/OTEd/jradel/effective.html