Location: Ptuj, Slovenia (August 2020)
Observation periods:
Hypotheses:
Test parameters: One-tailed z-test for proportions, α = 0.05, Power = 90%
Using G*Power methodology with arcsine transformation for proportions
Sample size needed to detect abnormal lighting with 90% power:
Key finding for H₀ = 75% (normal behavior):
n = 144 random observations needed
Cohen's h = 0.647 (medium effect)
At 8.92 visible hours/day, this could theoretically be collected in 17 nights of observation (assuming ~1 observation per visible hour). However, true independence requires observations separated across multiple days/weeks.
When ignoring "off" sightings, consecutive "on" observations needed:
Key finding for H₀ = 75%:
k = 13 consecutive "on" sightings needed
Cohen's h = 0.647 (medium effect)
This ignores any "off" observations and only counts consecutive instances where the light is on. Using geometric probability: P(k consecutive | H₀=75%) must be < α, and P(k consecutive | H₁=98%) must provide 90% power.
| H₀ (%) | Cohen's h | Effect Size | Random n | Consecutive k | Raw Difference |
|---|
Legal Interpretation:
If normal behavior involves lights on 75% of visible hours, an observer would need 144 random observations to distinguish this from cannabis growing behavior (98% on) with 90% confidence and α = 0.05.
Alternatively, 13 consecutive "light on" sightings (ignoring any "off" observations) would provide equivalent statistical power.
The Cohen's h effect size is 0.647, which is considered a medium effect per Cohen's benchmarks.
Ptuj Police made zero recorded observations. Their warrant was issued on literally nothing.
The Five Pollyannaisms of Ptuj Police: