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Blog 8; Table and Graphs
October 12, 2019
For my field research study I created a table and a figure from the data I collected. When I collected the data I used two categorical variables. The first was the presence\absence of Hydrocotlye heteromeria in each of the quadrats I examined. The second categorical variable I used was wet\dry plot. I determined how many of the quadrats had the presence or absence of the species in each of the wet and dry plots. Since I am using categorical variables, and my study is a snapshot, natural experiment with 2 categorical variables I used a tabular method to determine my data.
I created an “Observed” data table including totals what the actual data I examined. I also developed an “Expected” data table and totals. I needed to create an expected data table to determine what I should have expected if the variables were unrelated. The “Expected values are what would be expected if the Null hypothesis were true and the variables were independent of one another. I then performed a Chi statistical test to determine if the relationship between Hydrocotyle and soil moisture levels was statistically significant. I determined that there is evidence that Hydrocotyle heteromeria is limited by soil moisture levels.
I also used the percentages of Hydrocotyle presence and absence that I found from each of the plots to create a figure. The figure is an easily identifiable way to quickly check how the counts and variables in the data table relate to one another.
The only problem I encountered when doing the table and the graphs was the fact that the course actually didn’t contain any material on how to process data information depending on which of the study methods we chose to use. I had to consult the professor of the course to determine the correct statistical test needed to analyse my study data. The table information and statistical testing was fairly straight forward after I completed the data counts. The outcome of the research is exactly what I had expected after reading literature. Hydrocotyle is limited by soil moisture levels. I didn’t take into account the nutrient levels in this study, but I would however like to learn more about their effect on this interesting species.
