Table 2 Summary of the signal detection and determination capabilities of vessel-GNSS-A and daily-GNSS in 2021

Observation frequency (f)

4–6 times/year

365 times/year

Standard deviation (σ)

1.5 cm

0.5 cm

Trend only

95%CL of determined trend

6.0 cm/year (1-year obs.)

0.5–0.8 cm/year (4-year obs.)

0.2 cm/year (1-year obs.)

0.03 cm/year (4-year obs.)

95%CL of detectable difference of trends

1.0–1.5 cm/year (4-year obs.)

0.35 cm/year (1-year obs.)

0.05 cm/year (4-year obs.)

Event only

Effect size (γ = 0.8 and α = 0.05)

3.0 cm (± 1-year obs.)

0.1 cm (± 1-year obs.)

(For keeping a false positive below 0.05, threshold of -Δc-AIC should be set about 10.)

Trend and event (6-year obs.)

False negative

0.7–0.2 (for a signal of 4.5–6.0 cm (3σ–4σ))

0 (even for a signal of 0.5 cm (1σ))

95%CL of determined trend

1.8 cm/year (1.2σ/year)

0.1 cm/year (0.18σ/year)

Standard deviation of determined event size

1.5 cm (1σ)

0.08 cm (0.15σ)

90th percentile of determined occurrence time

 ± 0.5 year (for a signal of 6.0 cm (4σ))

 ± 0.1 year (for a signal of 2.0 cm (4σ))