The first step AUSRIVAS will perform is validating your data. Typical errors encountered at this stage may include missing data, incorrect invertebrate codes, misspelled habitat variable names, missing some required invertebrate taxon codes and missing predictor variables. If AUSRIVAS detects any errors in the variable names or in the data, the program will stop and the list of detected errors will appear. A more detailed explanation of some typical errors and the resulting windows follows.

 

4.5.1 Errors/warnings in input data

Warning - missing taxa

A window similar to the following will appear if your bug data set does not contain all the taxa codes required by a particular model. Your data set may not contain certain taxa because they were not collected, in this case AUSRIVAS will add them (with zero values) to your data set before running the model, and will inform you in a 'warning' dialog as shown below.

 

 

Error - missing predictor variable

If a predictor variable required by a model is missing, the model cannot run and you will get an error dialog similar to that shown below. A predictor variable can be deemed 'missing' if you have omitted it from your data set, or if you have spelled the variable name incorrectly. Changing the (correct) spelling of the “LATITUDE” variable to “LAT” generated the example below.

A list of the required predictor variables for each model can be obtained via the 'Required Variables' option in the 'Model' menu. More information on this is given in the section on ‘Entering data’.

 

 

Error - site mismatch

If the site codes listed in the Bug Data file do not match exactly those in the Phys/Chem data file a window similar to the following will appear explaining the error.

 

Error - blank data cells

It is important that there are no blank cells, as a site assessment cannot be produced for sites with blank cells in either the invertebrate data or the predictor variables. AUSRIVAS highlights any cells with blank data in the input data sheets in blue. If data is not inserted in these blank cells before a model is run, you will get an error as shown below. The error description tells you in which sheet ("Bug Data") and which row (Site 012) and column (MM999999) the blank/invalid cell occurs.

 

 

4.5.2 Is your data within the experience of the model?

Once the errors in the input data have been corrected the model can be restarted. If your data then pass the validation checks AUSRIVAS will proceed to the predictive calculations.

AUSRIVAS will now check if the test data are within the experience of the model you have chosen. That is, are there suitable reference sites with which your test sites can be compared? Your test sites may appear to be outside the experience of the model if;

•The wrong model for the season of sampling was chosen (or two seasonal data sets were combined incorrectly for a combined-season model, which will result in incorrect values for the predictor variables);

•Incorrect values (e.g. incorrect units of measurement used) have been entered for the predictor variables or;

•It may be that the model has no suitable reference sites with which to compare the test data, AUSRIVAS will provide a warning (see below).

 

 

Site 011a above is coloured red and the text beside the site code reads "This site is outside the experience of the model (Chi2 0.001)" and no output is provided for that site. Sites 012 and 014 are coloured orange and when the curser is placed over the site code a text box appears with the words "Warning: This site is nearly outside the experience of the model (Chi2 0.01). In this case an output is provided but interpretation should proceed with caution because the site data is nearing the limitations of the model. Chi2 0.001 and 0.001 relate to the Chi squared test performed on the data. For further information on the Chi squared test, refer to ‘What is the Chi squared test?’ in 'Frequently Asked Questions'.