The WRAS ANOVA system is a web-based statistical tool for comparing and analyzing Reef Check data. ANOVA (Analysis of Variance) is a widely applied statistical technique in biology, used to determine whether different types of experimental treatments or ecological factors cause significant variations in the behavior of biological systems (for more on ANOVA click here). WRAS ANOVA allows the user to assess whether groups of Reef Check surveys separated by geographic distance and time record significant differences in a Reef Check biological indicator (for more on Reef Check ANOVA click here). By using this tool, one can evaluate if the coral reefs in a particular site or country are degraded in comparison to another site or country, or if particular sites or areas show declines or improvement over time.
Instructions
Read the following instructions, and then click the Continue button below to do an analysis:
Once Continue is pressed, the ANOVA web-form page will appear.
This form allows users to select subsets of data from the Reef Check database for analysis.
The results of the ANOVA analysis are then computed and presented together with associated diagnostic plots.
Once in the web-form , first select the quantitative variable to be used in the ANOVA:
From the pull-down list of quantitative variables, select a monitored indicator species of interest for analysis.
This list includes 43 invertebrate and fish species; analyses are based on (log-transformed) abundance estimates of the selected indicator organism.
Second, select the factors on which the analysis will focus:
Select a first variable from the pull-down list of Factors (eg. Country).
Select a second categorical variable from the pull-down list of Sub-Factors (eg. Year).
Third, apply any necessary data filters to limit the spatial and/or temporal extent of the dataset used in the analysis:
Click to toggle between available geographical filter types. Data can be selected by Region, Sub-Region , Country, or any combinations of these filters. Select those entries from the respective pop-up lists to be included in the analysis. By default (if no filter is selected), all entries are selected (highlighted), meaning that data for all geographical areas in the database will be used.
To apply a time-based filter and analyze data for a specific period, specify a date range in the Year filter field. If no filter is selected, the entire time series of Reef Check data will be employed.
Finally, click the COMPUTE button to execute the analysis:
After a few seconds, a result matrix of F-ratio statistics and estimated probability (P) levels will appear.
Alternatively, an informative error message will result in the event that inappropriate user selections have been made, insufficient data is available for the analysis, or other analysis requirements have been violated.
Interpretation of the ANOVA results table:
Factor effects are deemed significant when associated P-values are less than or equal to 0.05 (5%).
Within Group effects consider whether selected factors in isolation account for observed variability in the data or have a statistically discernable effect.
Between Group effects consider whether significant interactions or synergistic action between factors occur (does the difference between survey sites depend on when the surveys were made?).
NOTE: Online Help is available:
Click the HELP ( ? ) button on the ANOVA web-form page to open up instructions in a separate browser window.
