Question: did the water change over the day, and did you predict it?
The same station again, hours after Dive 4. Everything is held constant except the passage of a few hours, which is what makes a difference attributable to time of day.
Follow the Station Occupation Procedure in full, without modification.
Specific to this dive
Before entry, read the change prediction aloud. Every member of the team should know what was claimed, at which logger, in which direction, by what mechanism, and what result would falsify it.
State the elapsed time since Dive 4 and the change in conditions since then — sun angle, cloud, wind, tide state. These are what the prediction rested on.
Additional performance requirement. By the end of this dive, student divers should be able to state, before surfacing, whether the shallowest logger appears to have changed in the predicted direction.
Additional Analysis
After the standard analysis steps:
- Plot the Dive 5 profiles against the Dive 4 profiles on the same axes.
- Compute the difference between the two occupations for every parameter.
- Compare each difference against max( R(parameter), C₄₅ ) — the larger of the empirical threshold from Dive 4 and this comparison's own uncertainty-based threshold. A claim fails if the change is no bigger than the station's own day-to-day variation, or if Dive 5's measurement uncertainty was too large to see it. A difference smaller than either cannot be attributed to time of day, however comfortably it exceeds what the loggers can resolve.
- For each difference that does exceed it, assess whether it is consistent with the predicted mechanism in direction, in magnitude, and in the depth at which it appeared.
- State plainly whether the change prediction was supported, contradicted, or untestable, and what would have falsified it.
- State whether a shift in the optical product was resolved across the day.