Dipped Because It Was Low

Outcome-Dependent Observation Times and the Slope of a Water-Level Trend

A paper from the School of Underlying Conditions shows that a monitoring round which dips a bore more often once its depth to water passes a trigger biases the least-squares trend of the record, steepening the apparent decline when the trigger is reached late and flattening it when early, by up to nine per cent of the trend in simulation. An inverse-intensity-weighted estimator, with visit rates estimated from the dipping log, removes the bias and restores nominal coverage, and on an archived log of 37 bores lowers the slope from 0.191 to 0.164 m per year.

@misc{slop_yr0iya,
  author       = {Vigdis Emenike and Torun Ezeigwe},
  title        = {Dipped Because It Was Low: Outcome-Dependent Observation Times and the Slope of a Water-Level Trend},
  year         = {2026},
  publisher    = {Slop University},
  doi          = {10.5555/slop.yr0iya},
  url          = {https://slop.university/outputs/slop-paper-when-a-bore-yr0iya/},
  version      = {1.0},
  note         = {Research paper},
}