What use is a preliminary report?
In some situations, the DNA sequences we get back from a sample are not enough to get a complete picture of the community. These results can still be useful, so we generally put them into a report and label it “preliminary”.
If your report is labeled preliminary: the DNA evidence demonstrates that your sample contains the organisms listed in that report. You can rely on these results just like any DNA sequencing test.
On the other hand, we’re not as confident in these cases about the organisms that we didn’t find in your sample (negative results, e.g. the absence of a parasite). If the report is labeled preliminary, it means there were technical issues with the data that may make the test less sensitive than usual.
Why re-test the sample?
In these cases we sometimes re-run the sample to get a more complete picture of the community in the tank. This isn’t because the preliminary report was wrong. In fact the preliminary report often looks very similar to the result we get back after re-running it.
The reason for re-running these samples is just to double check for the presence of any parasites we might have missed the first time. We want all our clients to get results they can be confident in, so if the data are questionable we sometimes re-run the sample to be sure.
Why upload the preliminary report if it’s not accurate?
The preliminary report is not wrong or inaccurate. Its just likely to miss rare members of the community, which might include parasites or other pests if they are present in the tank.
The preliminary report is just incomplete, but an incomplete picture can still be useful. Sometimes these reports already reveal useful details such as the presence of a parasite, or unusually high levels of dinoflagellates.
We upload these reports because we recognize that our clients’ data are time-sensitive, and we want to deliver their data as soon as they’re available. Its up to clients to decide whether to act on the preliminary information or wait for a re-test of the tank.