Tau-U Effect Size Analysis | Oura Digital Twin

SUMMARY

Effect Size Summary (A vs B+C)

TAU-U: Mean RMSSD

Large

0.695

Large effect | p<0.001 (trend-corrected)

A vs B+C | NAP=94.4%

TAU-U: Lowest Heart Rate

Large

0.693

Large effect | p<0.001 (trend-corrected)

A vs B+C | NAP=93.5%

TAU-U: Average Heart Rate

Large

0.666

Large effect | p<0.001 (trend-corrected)

A vs B+C | NAP=92.5%

TAU-U: Sleep Efficiency

Moderate

0.515

Moderate effect | p<0.001 (trend-corrected)

A vs B+C | NAP=81.3%

RESULTS

Tau-U Results: All Comparisons

Comparison	Metric	n_A	n_B	Mean_A	Mean_B	Dir	Tau-U	95% CI	p-value	Effect	NAP	Note
A vs B (Jakavi Effect)	Mean RMSSD	67	22	10.0	10.9	▼	-0.192 *	[-0.471, +0.088]	p<0.001	weak	62.7%	⚠ corrected
A vs B (Jakavi Effect)	Lowest Heart Rate	64	19	76.7	72.9	▼	-0.114 *	[-0.411, +0.184]	p=0.046	weak	69.7%	⚠ corrected
A vs B (Jakavi Effect)	Average Heart Rate	64	19	85.2	81.4	▼	-0.162 *	[-0.459, +0.136]	p=0.005	weak	69.1%	⚠ corrected
A vs B (Jakavi Effect)	Sleep Efficiency	64	19	78.6	79.9	▼	-0.018	[-0.316, +0.279]	p=0.749	weak	62.4%	⚠ corrected
B vs C (BB Marginal Effect)	Mean RMSSD	22	181	10.9	28.1	▲	+0.954 *	[+0.698, +1.000]	p<0.001	very large	97.7%
B vs C (BB Marginal Effect)	Lowest Heart Rate	19	178	72.9	59.4	▲	+0.886 *	[+0.612, +1.000]	p<0.001	very large	94.3%
B vs C (BB Marginal Effect)	Average Heart Rate	19	178	81.4	68.3	▲	+0.868 *	[+0.594, +1.000]	p<0.001	very large	93.4%
B vs C (BB Marginal Effect)	Sleep Efficiency	19	178	79.9	83.4	▲	+0.539 *	[+0.265, +0.813]	p<0.001	moderate	76.9%
A vs B+C (Combined Post)	Mean RMSSD	67	203	10.0	26.2	▲	+0.695 *	[+0.535, +0.855]	p<0.001	large	94.4%	⚠ corrected
A vs B+C (Combined Post)	Lowest Heart Rate	64	197	76.7	60.7	▲	+0.693 *	[+0.530, +0.856]	p<0.001	large	93.5%	⚠ corrected
A vs B+C (Combined Post)	Average Heart Rate	64	197	85.2	69.5	▲	+0.666 *	[+0.503, +0.829]	p<0.001	large	92.5%	⚠ corrected
A vs B+C (Combined Post)	Sleep Efficiency	64	197	78.6	83.1	▲	+0.515 *	[+0.352, +0.678]	p<0.001	moderate	81.3%	⚠ corrected

DESCRIPTIVE

Phase Descriptive Statistics

Phase	Metric	n	Mean	SD	Min	Max
A	Mean RMSSD	67	10.0	2.4	5.0	18.4
A	Lowest Heart Rate	64	76.7	5.7	64.0	96.0
A	Average Heart Rate	64	85.2	6.8	69.8	113.9
A	Sleep Efficiency	64	78.6	3.4	71.0	91.0
B	Mean RMSSD	22	10.9	2.2	6.9	17.7
B	Lowest Heart Rate	19	72.9	4.0	67.0	84.0
B	Average Heart Rate	19	81.4	4.2	76.4	96.4
B	Sleep Efficiency	19	79.9	4.0	69.0	87.0
C	Mean RMSSD	181	28.1	8.3	8.0	55.4
C	Lowest Heart Rate	178	59.4	6.9	35.0	86.0
C	Average Heart Rate	178	68.3	7.1	56.5	97.8
C	Sleep Efficiency	178	83.4	5.9	58.0	92.0

METHODOLOGY

Methodology & Interpretation

Methodology

Tau-U (Parker, Vannest, Davis & Sauber, 2011) is the recommended effect size for single-case experimental designs (SCED). It quantifies the degree of nonoverlap between phases while optionally correcting for baseline trend.

Interpretation Scale

|Tau| < 0.20 = Weak

0.20 – 0.60 = Moderate

0.60 – 0.80 = Large

> 0.80 = Very large

Key Details

Positive Tau = improvement (direction-adjusted per metric)
Baseline correction: If Phase A shows a significant trend (Kendall tau, p<0.05), Tau-U is corrected by subtracting the baseline S statistic. A ⚠ symbol marks corrected values.
NAP (Nonoverlap of All Pairs) is a complementary measure: probability that a random Phase B observation exceeds a random Phase A observation (after direction adjustment). NAP > 0.93 = large, 0.66–0.92 = medium, < 0.66 = weak (Parker & Vannest, 2009).
* = statistically significant at p < 0.05

Phases

Phase A (Pre-treatment): Jan 08 – Mar 15, 2026
Phase B (Jakavi only): Mar 16 – Apr 07, 2026
Phase C (Jakavi + Beta-blocker): Apr 08, 2026 – present