Fern gametophytes in varying densities
5. Data Analysis
In the data analysis, you will make 2 graphs to address the questions posed in this lab.
You will use the information provided below to decide which type of graph to use to address the questions. Once you have the analysis done, head over to the assignment.
Figure 1 – Does gametophyte density affect sex expression in C. richardii?
- You will use the class data because having a sample size >1 is important for reliability of data, but also gives us an idea of how much variation there is!
- What is your independent variable (IV)? Which is more biologically meaningful: gametophyte density or plate letter? If you look at the density of the plates, you will see that no 2 groups have the same density for Plate A, for example. Therefore, it is likely more important to plot each data point rather than the mean. Keeping each density point will give a better picture of the relationship between density and sex expression.
- Dependent variable (DV): You only need to plot the % male gametophytes. The male expression is the one that could be affected by gametophyte density, so biologically this makes the most sense to plot. Why not both male and hermaphrodite? The data points are not independent (i.e., 100% – male% = hermaphrodite%). We would be adding unnecessary clutter to our figure by adding the other data.
- What type of data are your IV and DV?
Figure 2 – Does gametophyte density affect C. richardii hermaphroditic gametophyte size?
- First, you need to calculate the mean and standard deviation of the 4 gametophytes measured at each density.
- You will be making a similar graph to that in Figure 1, the only difference being the dependent variable.
- DV = mean width of hermaphroditic gametophytes
- Because you are plotting the mean, you need to include the variability!
